Process for treatment of crude oil, sludges, and emulsions

ABSTRACT

The present invention provides a process for treatment of petroleum/crude sludge for removal of bound and unbound water thereby facilitating recovery of non volatiles free product hydrocarbons in a range of about 96 wt. % to 100 wt. % along with unbound water having turbidity at least below 20 NTU. The process for treatment of sludge facilitates recovery of almost 100% solvent along with entire bound water in a range of about 99 wt % to 100 wt %. The process for treatment of sludge facilitates recovery of free water in a range of about 94 wt. % to 99 wt. %. The process for treatment of sludge also facilitates recovery of solvent to be reused in said process. The present invention further provides a process for treatment slop oil containing water, solids, salts and limited hydrocarbon content less than 10,000 PPM for recovering usable water therefrom by an effective and economically viable process. The process for treatment of slop oil is capable of bringing down turbidity value thereof in a range of 90 wt. % to 99 wt. %.

FIELD OF THE INVENTION

The present invention relates to processes for treatment ofpetroleum/crude sludge, emulsions and slop oil. More particularly, thepresent invention relates to a process of removal of bound and unboundwater from petroleum/crude sludge, emulsions and slop oil comprising ofhydrocarbons, bound water, unbound water, dissolved and un-dissolvedsolids, into different pure salable streams, particularly but notrestricted to petroleum industry.

BACKGROUND OF THE INVENTION

Petroleum crude comes out of oil wells invariably with water, dissolvedand un-dissolved solids and sulfur bearing compounds containing partlyboth bound water and unbound water. This petroleum crude is thereaftertreated at group collection centers (GCCs, hereinafter) of oil companieswherein firstly the petroleum crude is de-sulfurized and then unboundwater are removed along with un-dissolved solids. However, GCCs do notremove bound water and dissolved solids except in cases wherede-emulsifiers are used. Presumably, because desalting of crude leads toadditional formation of emulsion with bound water, crude with boundwater is sent to oil wells.

GCC is specifically required to remove sulfur with most of theun-dissolved solids from the crude and remove entire water to bring downthe crude water content below 5000 ppm before sending it to refineries.The process of removal of water mainly involves allowing the crude tosettle in a settling tank wherein the top layer, middle layer and bottomlayer are formed. The top layer contains pure crude that is sent torefineries for further treatment. The middle layer contains waterbearing emulsion that is sent to tank where it is heated subjected tohigh voltage oscillating electric field and optionally with use ofde-emulsifiers where the purpose is to remove maximum water in leasttime. The bottom layer normally contains oily water with un-dissolvedsolids which is known as slop oil. Being a pollutant, often the slop oilis sent to abandoned oil wells for storage through pipe lines.

In refineries, production, transportation, storage and refining of thecrude oil mostly create sludge. Sludge is generally a tightly heldviscous emulsion of oil, water and solids wherein the solid contentcould vary widely. Whenever oil and water is mixed and agitated, sludgegets formed. In refineries, sludge is also formed in the desalting unitwhere crude is washed with fresh water to remove Alkalis that hadingressed with seawater. Also, sludge gets produced in hydro-crackers,crude storage tanks, slop oil, API separators and the like. Normally 1.6kgs. of sludge is produced per tonne of crude. As per a 1992 US-EPAreport, by and large petroleum refineries unavoidably generate about30,000 tons of oil sludge waste streams per year per refinery. More than80% of this sludge comes under the EPA hazardous waste nos. F037 andF038. In India, more than 2.62 lac tonnes of sludge is produced in ayear.

Sludge also gets formed, when water in crude is vigorouslyagitated/sheared by transfer pumps. Being heavier than light oils, ittends to settle at the bottom of ship, load, but gets removed from ship,when crude is pumped out at the refinery. Apart from that, we have tanksludge, which is a solid layer that accumulates with time at shipbottom, and is removed once in 5 years or so. Typically a 60-M tankdisgorges 1,000 MT of material. About 85 to 90% of it constitutes heavyhydrocarbons like paraffin, asphalt, micro-crystalline wax, etc. Oftenthis material is removed using high pressure water jets. Sludge alsogets generated in post refinery operations. When heavy liquid fuels likeLSHS or furnace oil are used for power generation through low speed DGsets 0.5 wt % to 1 wt % sludge gets formed. These DG sets could eitherbe land based or marine. Sludge also gets produced in waste-oilre-conditioning plants. Formation of sludge is a great problem inoverall world.

For example, Texaco, (acquired by Chevron in 2001) after oil drillingoperations from 1964 to 1990, seventy billion litres of toxic petroleumsludge pools were abandoned in Ecuadorean Amazon rainforest without anyremedy. This sludge came from drilling operations per se and not fromproduction. Chevron has a patented technology for treatment of sludge asdisclosed in U.S. Pat. No. 4,689,155. However, still the sludge wasdumped into streams and rivers that local people depended for drinking,bathing and fishing. It dug over 900 open Air, unlined waste pits thatstill seep toxins into the ground. This sludge contained chemicals likebenzene & polycyclic aromatic hydrocarbons. What's worse is this dumpingwas done intentionally to cut corners and save an estimated US $3 perbarrel. The company saved US $1.32 billion, but it led to 30,000Ecuadoreans suffering, with 1,400 of them dying. This could lead to10,000 more deaths by 2080.

In case of orient region of Ecuadorean rainforest, which once supported30,000 people, the land itself has become toxic and water systemcontaminated. Almost any kind of food from this region, whether it'sfanned, domesticated, caught in the wild or in water is unsafe to eat.Local economies and communities have collapsed. Eighteen years agolocals filed a class-action law-suit. Damages had been assessed at US$27.3 billion. Locals own their case and Chevron was asked to pay US $18billion. Rather than take responsibility and pay up for thisenvironmental disaster, Chevron refused to pay and is wagingunprecedented public relations and lobbying campaigns to avoid having toclean up the mess.

In case of PdVSA, the Public Sector Oil Company in Venezuela. In August1999, it was slapped with US $1.5 billion in environmental liabilities.Amongst other things, it was asked to clean up 15,000 oil pitscontaining contaminated sludge from oil wells. This alone cost theCompany US $1 billion. Under pressure from courts, this Company whichhad traditionally ignored the environment has now started cleaning-upoperations & pledges to rank environmental protection as one of its topmost goals.

In case of Russia, it generates more than 3 million tonnes of PetroleumSludge per year, more than 33% of that coming from oil wells alone.Russian oil & gas industry is the 3rd largest contributor toaccumulation of industrial wastes in that country. Russia has 7,000abandoned oil wells. It has 416,000 km of oil pipelines that often getdamaged due to corrosion. Every year it faces 50,000 to 60,000 pipelinerelated accidents, leading to a leak of 15 million tonnes of oil beforeautomatic flow blocking mechanisms get activated. About 30% of this endsup in rivers and lakes, i.e. 4 to 5 million tonnes a year. In 1994, atKomi alone 0.1 million tonnes of oil got spilled from a single pipelinerelated accident. In 1993 at Tyagan, in Tyumen region, a single pipelinerelated incident led to a spillage of 0.42 million tonnes of oil. Russiahas lagoons holding millions of tonnes of sludge. Western Siberia hasmore than 3 million tonnes of slop. Tatarstan has over 2.5 milliontonnes. Bashkortostan has 700 lagoons with 2 million tonnes of sludge.Land being cheap, storage of sludge in lagoons cost US $20 to $40 pertonne depending on location. They burn away most off their sludgecausing extensive air pollution. Russia has 27 refineries with totalcapacity of 300 million tonnes. At its Saratov Refinery, lagoons covermore than 150 ha. The content of oil in its ground water is 7.2 gramsper litre. US companies alone are currently providing sludge disposalservice in Russia worth more than US $90 million per annum. Russia paysbetween US $28 to $360 to dispose off a tonne of sludge, depending onhow far the area is from city & also on the kind of technology andequipment used.

The cost of a Russian custom-made sludge processing system built withforeign components start from US $5 million onwards. These are mostlyde-emulsifying units based on settling tanks, centrifuges & decanters.Oil skimmed from therein gets used in barges & pumps. They also usebio-remediation & incinerators. For de-emulsification combined withbio-remediation they pay between US $160 to 200 per tonne. Forinnovative technologies like ultra-sound treatment they pay US $300 pertonne.

Since sludge is difficult to dispose off, till recently refineries weredumping it in tanks, ponds & lagoons. Most refineries in developing andunder-developed countries continue to that even till the present date.Typically, such lagoons are 4 ha. in size & contain about 1.2 to 1.6lakh tonnes of sludge. Several of them contain sludge since 1896.Sludges in such old lagoons are known, as “weathered sludge” With age,they tend to get homogenized.

In developed countries like the US, fresh storage of sludge in ponds orlagoons is prohibited, unless they are lined with non-permeablematerials. Even that is strongly discouraged. That's because surroundingsoil & groundwater get adversely impacted. Evaporation of volatiles toocauses strong odour & air pollution.

In 1980, US Congress enacted the Comprehensive Environmental Response,Compensation & Liability Act. This created a tax on chemical & petroleumbusinesses and the money thus collected went into a large trust known asSuperfund. That money paid for the cleaning up of all hazardous wastedisposal and spill sites, like the petroleum sludge lagoons. In 1995 thetax on industries expired. But the Superfund Programme continued. Todaymoney is appropriated from the general tax revenue, to fund it. US-EPAadministers this fund in co-operation with individual states.

Recently, cleaning-up of sludge ponds & lagoons has emerged as alucrative commercial business. Refineries are keen to recover oil fromsludge. When that's not possible, they are keen to extract its energy.When even that's not possible, they try to convert it into innocuoussubstances, at the least cost. There are various efforts seen in the artfor cleaning-up of sludge using various techniques.

Use of de-emulsifiers/chemicals is seen in the art for breaking of thesludge. For example, Chinese patent document CN101786776 to NormanKevin, Elk Point discloses deep treatment process wherein theoil-containing sludge is introduced into a regulation pool followed byadding of hot water and subsequent stirring thereof such that thefluidity of oil-containing sludge is improved. The sludge is furthertreated in cyclone desalter and sent into a modulation tank where apredefined quantity of demulsifier is added followed byde-emulsification at an appropriate temperature. Also, Czechoslovakianpatent document CS8702260-A to Baxa J entitled “Oil dehydration anddesalting—by adding distillation slops and de-emulsifying vacuumdistillation” discloses use of de-emulsifiers.

M/s. Smith & Loveless Inc. treats refinery sludge with chemicals andaeration. M/s. Lenntech Petrochemical Company from Netherlands useschemicals, solvent extraction, membranes, filtration, floatation,flocculation, reverse osmosis, etc. to recover oil. M/s. Reverse Oil, aUkrainian-American Joint Venture is desludging “Ukrtatnafta” sludgeponds since 1996, with a plethora of chemicals, merely to minimize itsadverse environmental impact. However, sludge breaking withchemicals/de-emulsifiers doesn't always affect 100% separation. Also,the use of de-emulsifiers is unfit for further use within refineriesunless the recovered oil is predominantly free from water.

Alternatively, a technique of heating the sludge with solvent,preferably with Azeotropic solvent mixtures, is also seen in the art.For example, German patent document DE 19936474 to Bereznikov Anatoliprovides separation of oil-containing sludges by heating with a solventand recycling the solvent is effected using a solvent (e.g. toluene)forming a heterogeneous azeotropic mixture with the aqueous component.The mixture is steadily mixed to give slurry which is then heated to itsboiling point. The saturated vapour is condensed and the aqueouscomponent and the solid residue removed, this being continued tocomplete water separation by controlling the temperature increase. Also,Spanish patent document ES2047129T3 to Richter Gedeon Vegyeszetdiscloses dehydration process employing Azeotropic distillation and moreparticularly it relates to a process for the vigorous dehydration ofsubstances or mixtures, primarily condensation reaction mixtures, (e.g.direct esterification, direct acetal formation, direct ketal formation)using continuous Azeotropic distillation. Further, US Patent documentU.S. Pat. No. 3,669,847A to Dynamit Nobel Ag discloses process forseparating steam-volatile organic solvents from industrial process wastewaters wherein Steam-volatile organic solvents are removed from processwaste waters by intimately mixing the process waste waters with steam toform an azeotropic steam mixture, withdrawing the Azeotropic steammixture from the resultant mixture of steam and water, and condensingsaid Azeotropic steam mixture.

Companies like M/s. CEVA International Inc. & M/s. E & I Technologies,Inc. recover oil by centrifuging sludge. In collaboration with M/s.Petro-Waste Services, Inc. (PWS), CEVA offers equipment in 2 sizes. Oneprocesses 200 tonnes of sludge/day, while the other handles 475 tonnesof sludge a day. Some of these are mobile units. Often when sludgeresolution is not possible, refineries incinerate them. Due to highwater content, here burning is often supported with supplementary liquidfuels. M/s. W. N. Best makes incineration systems for processing 0.38 to26.5 tonnes of petroleum sludge/hour. Many modern refineries dump theirsludge in Coker Plants, where fuel is partially recovered. Hence theydon't generate sludge. Pollution prevention through non-generation isconsidered to be most profitable. They create what's known as Pet Coke.However, the coke oven plants produce high sulfur contents.

Bioremediation is however emerging as major trend. Here sludge isuniformly mixed with soil, such that its total hydrocarbon content islimited to ˜3 wt. %. Naturally existing bacteria in soil then degradeshydrocarbons into CO2 & H2O over a period of few years. To acceleratethis, one increases the supply of air, moisture & nutrients into thesoil. To increase nutrients, one supplies nitrogen & phosphorus basedfertilizers. A certain density & variety of bacteria also helps. Withall these, one tries to achieve a significant reduction of hydrocarbonsin soil within about a year. This process is also known as “landfarming”, since one works sludge into land with a view to achieve itsfinal disposal through the slow process of bacterial action.

Biopiling is a further improvement in this field where homogenous sludgeand soil mix are placed over an impermeable base of natural clay, alongwith wood chips to improve permeability. Perforated pipes are connectedto a blower or vacuum pumps to aerate the soil pile. Leachate collectionsystem is also incorporated for uniform addition of water and nutrient.

Globally M/s. Biogenie, M/s. Envirosoil Services Ltd. and M/s. WillacyOil Services Ltd. are active in this field. The LTTD process ofEnvirosoil treats soil with sludge in a plant and once hydrocarboncontent in soil is reduced below the acceptable level of 15 ppm, it istransferred to land. Willacy is very active in Middle East and Turkey.

In India, M/s. Tata Energy Research Institute (TERI) took 7 years todevelop “Oilzapper”. That's an efficient bacterial consortium, developedfrom 5 bacterial isolates, immobilized over powdered corncob. Itefficiently degrades oil based hydrocarbons within about a year. Thistechnology know-how has been transferred to M/s. Shriram Biotech Ltd.,Hyderabad & M/s. Bharat Petroleum Corporation Ltd., Mumbai. Oilzapperhas successfully degraded more than 10,000 tonnes of petroleum sludge inIndia over the last 2 years. Globally, bioremediation costs between $73to $641 per tonne of sludge.

However, even bioremediation technique has certain limitations. Firstly,the bioremediation process leads to entire loss of valuable hydrocarbonwhich is highly undesired. Secondly, the bioremediation process ishighly expense and consumes a lot of time in waste disposal process.Also, the product obtained after remediation fails to convert waste intowealth as the product obtained after bioremediation treatment is of nouse.

Another deadliest pollutant is the slop oil which is normally an oilywater containing solids and salts. This water is treated at GroupCollection Centres (GCCs) prior sending it to refineries. Slop oil alsogets generated in refineries where the crude is added with fresh waterfor desaltation and removed using same equipments as that of GCC therebyadding unnecessary cost. Also, lot of hydrocarbon is lost in suchprocess in addition to generation of polluting slop oil.

This water being a pollutant is normally sent back for storage whereinthe stored corrosive water may leak out in addition to adding cost oftransport for discharging the corrosive water in sea water throughpipelines. Slop oil also has large implications on environment where itcontaminates sea water thereby effecting marine life. Further, slop oilis a major source which has always been neglected although being avaluable source of oil and water both.

For instance, Russia has more than 4,16,000 km pipeline that often getsdamaged due to corrosion causing 50-60,000 pipeline related accidentsthereby leading to leak of millions of tons of oil before automatic flowblocking mechanisms get activated. About 30% oils ends in rivers andlakes thereby generating slop oil. In 1993, Tyagan in Tyumen region asingle pipeline related incident lead to spillage of 0.42 million ofoil. In 1994 at Komi alone, 0.1 million tons of oil got spilt from asingle pipeline leakage.

Slop oil even comes from cleaning of oil contaminated equipmentsincluding cleaning of oil carrying ships. Even in industries apart fromoil industries, the industries where oil is used as coolant or forlubrication slop oil gets generated.

Conventionally centrifuge technique is used for treatment of slop oil.For example, German patent document DE4205885 to Meiken, Bernardentitled “Recovery of water, gasoline, heavy oils, and solids from slopoils or oil emulsions” discloses use of two-phase decanter forcentrifuging of slop oil/emulsions wherein Slop oil is heated to105-135° C. in a heating circuit formed by a heater, column, and pump.The gases and steam are then drawn from the top of the column, and, fromthe bottom of the column, heated oil slops are taken, cooled, and, in atwo-phase decanter separated into a centrifuged clean oil-phase and asolid phase. Also, Russian patent document RU2217476 teaches processesof the oil-bearing slimes refining and extraction hydrocarbons from themfor refining of the liquid and pasty oily slimes, in particular of thebottom sediments, resistant oil-water emulsions, intermediate layerscontaining a fair quantity of mechanical impurities. The method providesfor dilution of the oily slimes with petroleum, its heating andseparation in the three-phase decanter centrifuge for petroleum, waterand a concentrate of mechanical impurities. Residual water is separatedfrom petroleum with the light oil fractions in the distillation column.Further, Chinese patent document CN100582031 to China Nat Petroleum Corpdiscloses a process for processing and utilizing for oil fieldoil-containing sewage sludge. The invention relates to the process andutilization method of the oily sludge wherein the horizontal centrifugevia a secondary lift pump is used for dehydration. The dehydrated waterenters the coming liquid pipeline of the sewage disposal system aftercentrifuge operation.

However, centrifuge technique is not without limitations. There aregenerally two types of centrifuges that are used in tandem, namely adecanter and disc stack centrifuge. The disc stack centrifuge hasadvantages of higher G but it is inefficient when slop oil contains moreamount of solids. The decanters enhance density difference but they failin case of handling of heavy crude/extra heavy crude contaminated waterthat has oil density equal to water density. Centrifuge enhancesbuoyancy but reduces residence time due to which it is effective onlywhen the particle size is more and drag is less. Moreover, surfacecharge of the oil particles tends to prevent oil particles to coalesceand come together. Further, the centrifuge can handle ultrafineparticles only until population density is very large. However, when thepopulation density falls below a particular level mean free pathincreases so much that coalescence of droplets fails to occur within theresidence time permitted. The main fact is that that the centrifuge canmake separation only when there is coalescence. Hence, centrifugetechnique substantially fails to work as intended when the slop oilcontains either ultrafine oil droplets or highly viscous oil dropletscontaining solids and bound water therein.

Alternatively, use of filtration technique is also seen in the art forsludge treatment. For example, Canadian patent document CA1202223 toAmsted Industries Incorporated discloses a deep bed type filtercontaining gravity separator. The bed is agitated and dislodged oilentrapped in filter bed. Where the oil in the water is unusually viscousor has a waxy, tarlike, or sticky consistency, for example, rejuvenationof the filter bed is enhanced by the addition of a small amount of asolvating liquid to the oil-water mixture before filtering. Also,GB1340931 to Beavon D K teaches a treatment method for oil-water mixturecontaining also oily particulate solids which is treated by passing itthrough a granular filter medium to remove the particulate solidswherein the filtrate obtained is being water or a mixture of water andoil. The next is to periodically solvate oil from the granular filtermedia by passing an oil stripping media through the bed in the samedirection as the oil-water mixture without affecting the integrity ofthe filter medium followed by backwashing the filter to remove the nowoil-free solids. The oil-water filtrate obtained may then be separatedby gravity settling.

However, filtration technique substantially fails to produce oil freewater without any chance of total separation of salable quantity of oilwhen there is large population of ultrafine droplets of sub-micron size.Further, the filtration technique is highly time consuming consideringthe pore size of the filtration medium. Moreover, regeneration offiltration medium is a highly tedious and time consuming task.

Optionally, coagulants or flocculants are also used to overcome abovedisclosed disadvantages of centrifuge and/or filtration. However, thesecoagulants/flocculants deteriorate or contaminate quality of oil.Moreover, the addition of coagulants and flocculants is a slow processand time consuming. If the oil droplets are held by water then neitherfiltration nor centrifuge will work unless the emulsifiers are used. Forexample, entire fats cannot be removed from milk by filtration orcentrifuge because fats are hold by proteins which are emulsifier inthis case.

Use of air flotation techniques for removal of emulsified oil particleswas seen in the art. For example, a research paper entitled “The removalof emulsified oil particles from water by floatation” to ChristineAngelldou et al., Ind. Eng. Chem. Process Des. Dev., 1977, 16 (4), pp436-441, talks about use of air bubbles by air flotation technique forrecovery of oil particles wherein the floatation of emulsified oilparticles suspended in low concentrations in water has been studied. Twooils were used wherein the oil concentrations were up to 200 mg/L. Toeffect the separation various cationic surfactants were used in theflotation cell which was operated batch wise with an external totalrecycle. It was found that the rate of floatation in water was increasedwith addition of surfactant up to a limit. The presence of sea saltreduced the floatation rate. However, air flotation technique is notwithout limitations. Firstly, the air floatation is feasible only forthe oil concentrations up to 200 ppm and it can never go beyond said ppmlevel. Secondly, these techniques make use of surfactant that highlycontaminates the quality of oil and bound water. Further, removal ofsolid and bound water is impossible in the air floatation technique.

Accordingly, there exists a need of a process for treatment of apetroleum sludge that facilitates recovery of usable oil and usablewater from the sludge considering enormous volumes of the sludge whichis generally found as an untreated waste. Further, there exists a needof a process that removes bound water from the petroleum sludge apartfrom the use of de-emulsifiers which may work in rarest cases. Inaddition, there exists a need of a process for treatment of slop oilthat facilitates recovery of usable water from the slop oil consideringenormous volumes of the slop oil which is generally found as eitherphysically dispersed in the water or bound to water through anemulsifier. Further, there exists a need of a process that convertswaste slop oil into usable water by a cost effective way in addition torecovering usable oil therefrom.

OBJECT OF THE INVENTION

An object of the present invention is to remove bound and unbound waterfrom petroleum/crude sludge and emulsions, comprising of hydrocarbons,bound water, unbound water, solids and dissolved salts into differentpure salable streams.

Another object of the present invention is to provide a process fortreatment of sludge that is cost effective and which facilitatesrecovery of pure oil and water as complete as possible withoutdeteriorating original composition/characteristics thereof.

Further object of the present invention is to provide a process fortreatment of slop oil to recover usable water from slop oil by aneffective and economically viable process.

Yet another object of the present invention is to recover usablehydrocarbons from the slop oil by an effective and economically viableprocess in addition to mitigating the problems of slop oil pollution.

SUMMARY OF THE INVENTION

In a preferred embodiment of the present invention, a process fortreatment of a sludge mixture is disclosed wherein the sludge mixtureincludes hydrocarbons with bound water, unbound water, dissolved andun-dissolved solids therein. The process for treatment of the sludgemixture comprises a first step of centrifuging the sludge mixture in afirst centrifuge provided if the sludge mixture splits into variouscomponents. The first centrifuge being a batch centrifuge forms aviscous hydrocarbon layer, a slop oil layer and a free flowinghydrocarbon layer. In next step, the viscous hydrocarbon layer isdesalted in a first desalter followed by optional treatment thereof in aheat based low volatiles stripping vessel for removing vapors of lowboiling liquid hydrocarbons therefrom. In next step, the vapors of lowboiling liquid hydrocarbons are condensed in a first condenser forobtaining low boiling liquid hydrocarbons along with water for use.Optionally, the crude hydrocarbons coming from a group collection centerare desalted in a second desalter for obtaining desalted product crudethereby removing bound water containing hydrocarbon layer that issubsequently mixed with the viscous hydrocarbon layer from the firstcentrifuge. In next step, the free flowing hydrocarbon layer is desaltedin a third desalter for entire removal of salts therefrom. In next step,the viscous hydrocarbon layer is treated in a homogenizer by adding afirst predefined amount of solvent for forming a volatiles freenon-viscous homogenized stream therefrom. In next step, BTX and Ashtests of the non-viscous homogenized stream are performed followed bytreatment thereof in an agitator cum homogenizer thereby adding a secondpredefined amount of solvent therein in accordance with the BTX and Ashtests results. In next step, the non-viscous homogenized stream iscentrifuged in a second centrifuge for separating a bound water dominanthydrocarbon stream, unbound water dominant or water free hydrocarbonstream and the slop oil therefrom. Optionally, the non-viscoushomogenized stream is treated in a hot insulated settling tank forremoval of water free solvent along with hydrocarbons therefrom. In nextstep, the unbound water dominant or water free hydrocarbon stream isheated in a first heating vessel thereby optionally adding a predefinedamount of free water. The first heating vessel operates at a firstpredefined temperature range thereby forming a first residual phase anda first vapor phase. In next step, the bound water dominant hydrocarbonstream is heated in a second heating vessel at a second temperaturerange thereby optionally adding a third predefined amount of additionalsolvent. The second heating vessel forms a second residual phase and asecond vapor phase. In next step, the first residual phase iscentrifuged in a hot centrifuge at a second predefined temperature forobtaining volatiles free desalted product hydrocarbons in a range ofabout 96 wt % to 100 wt % along with unbound water having turbidity atleast below 20 NTU. In next step, the second residual phase is treatedin the first heating vessel. In next step, the first vapor phase and thesecond vapor phase are condensed through a second condenser forobtaining at least 100% solvent, the bound water in a range of about 99wt % to 100 wt % and the free water in a range of about 94 wt % to 99 wt%. The solvent is reused in said process.

The first centrifuge reduces quantum of the sludge mixture with boundwater that requires further processing which reduces cost and time offurther processing. The free flowing hydrocarbon layer is about 41 wt %typically having 3,864 ppm water and 0.88 wt. % ash with calorific valueof 10,635 kcal/kg. The viscous hydrocarbon layer is having at least42.21 wt. % water typically having 8.61 wt. % Ash with CV of 5,210kcal/kg. The first centrifuge enhances separation between the componentspresent in the sludge by extending a period of residence time of thesludge thereby gradually varying revolutions per minute of the batchcentrifuge enabling collection of slop oil behind the viscoushydrocarbon layer.

The first desalter, the second desalter and the third desalter retainthe quality of hydrocarbons coming from different process streams andhence improve commercial value thereof. The first desalter, the seconddesalter and the third desalter prevent needless repetition of identicalprocesses done in the group collection center for removal of bound andunbound water from crude again into refineries after desalting of thecrude. The first desalter, the second desalter and the third desalterprevent ingression of water into various product hydrocarbon streams inrefineries thereby preventing accumulation of sludge in downstream ofsaid process and vessels from refinery onwards processes. The firstdesalter, the second desalter and the third desalter allow the groupcollection center to dispatch crude without salts and without having toworry about either disposal or processing of crude containing boundwater. The first desalter, the second desalter and the third desalterprevent corrosion of pipelines and tankers during transportation. Theheat based stripping vessel separates the low volatiles from the viscoushydrocarbon layer for preventing co-distillation thereof along with thesolvent during removal of bound water with solvent in downstream of saidprocess. Removal of the bound water from the viscous hydrocarbon layeralso allows removal of heavy metal, Ash and salts therefrom whicheffectively improves commercial value thereof. The BTX and Ash testshelp assists in determination of amount of solvent to be added in saidprocess.

The solvent reduces viscosity for removal of bound water from topmostlayer of the non-viscous homogenized stream on account of viscosity. Thesolvent help assists in homogenization of the sludge that in turn helpssampling and further helps in accurate determination of water and Ashcontent. The solvent is added in said process only for viscous portionof the hydrocarbons which substantially reduces overall use of solvent.The solvent is selected from the group of Benzene, Toluene, Xylene andsimilar Azeotropes of water. The solvent helps removal of the boundwater from the top most layer and has least possible thermal damage tothe product hydrocarbon stream in said top most layer. The solventstream and the second centrifuge mutually remove substantial bound waterfrom the viscous hydrocarbon layer at an ambient temperature. Thesolvent depresses the boiling point of the bound water. The solvent isadded in a range of about 1.8 to 100 times the weight of water presentin the sludge for removal of entire bound water. The solvent has a leftover weight ratio of solvent to hydrocarbon in a minimum range of 2.00to 6.00 for entire removal of the bound water at least temperature. Thebound water obtained is high quality usable water that requires minimaltreatment for being used as a drinking water. The first predefinedtemperature of the first heating vessel is in a range of about 90°C.-105° C. The second heating vessel is a multi effect evaporatorpreferably with thermal vapor recompression to avoid thermal cracking ofthe product hydrocarbon stream. The second heating vessel includes afoam breaker and an entrainment separator adapted to avoid entrainmentof hydrocarbons in condensate. The first heating vessel includes a foambreaker and an entrainment separator adapted to avoid entrainment ofhydrocarbons in the condensate. The second heating vessel maintains acontrolled rate of heating with an optimum ratio of residual solvent towater for entire removal of bound water from the hydrocarbon. The firstand second heating vessels are provided with waste heat for reducingcost of energy in said process.

The hot centrifuge is a hot settling tank that ensures adequatereduction in viscosity of hydrocarbons thereby allowing settling of freewater present therein over a period of time. The hot centrifuge has atemperature in a range of about 80° C. to 94° C. The hot settling tankmay be operated under high pressure so that operating temperature can beincreased to further reduce the viscosity of hydrocarbon that willfacilitate faster removal of free water without leading to boiling ofwater.

In an alternative embodiment of the present invention, a process forpre-treatment of slop oil is disclosed where the slop oil containswater, solids, salts and hydrocarbon content greater than 10,000 PPMwith or without bound water. The process for pre-treatment of slop oilcomprises an initial step of feeding the slop oil in a first settlingtank for phase separation thereby forming a substantially unboundwater-free hydrocarbon layer with or without salts, a water dominanthydrocarbon layer, and a slop oil layer having hydrocarbon content lessthan 10,000 PPM. In next step, the water dominant layer is treated in asecond settling tank by adding a predefined amount of alum therein. Thesecond settling tank forms a substantially unbound water-freehydrocarbon layer, a gelatinous oil bearing layer and alum containingslop oil having hydrocarbon content less than 10,000 PPM. Optionally,the gelatinous oil bearing layer is centrifuged in a third centrifuge byadding a predefined amount of solvent. The third centrifuge forms asolvent layer containing Alum along with solid coated with hydrocarbons.The solvent layer contains Alum that is being added to the first heatingvessel in said process. The third centrifuge helps to quickly separatesolvent cum hydrocarbon layers and gelatinous oil bearing layer fromslop oil.

In yet another alternative embodiment of the present invention, aprocess for treatment of slop oil is disclosed wherein the slop oilcontains water, solids, salts and limited hydrocarbon content less than10,000 PPM with or without bound water. The process comprises an initialstep of centrifuging the slop oil through a fourth centrifuge forobtaining the slop oil with low turbidity by connecting most oil presentin a thin top layer. In next step, the above slop oil from is treated ina high speed shear mixer by adding a solvent to form a mixture followedby centrifuging thereof in a fifth centrifuge for obtaining a waterdominant hydrocarbon layer and a solvent dominant hydrocarbon layertherefrom. In next step, BTX and Ash tests of the solvent dominanthydrocarbon layer are conducted for bound water followed by a heattreatment thereof in a third heating vessel and a fourth heating vessel.The third vessel has a predefined amount of solvent added therein. Thefourth vessel is having a predefined amount of free water added therein.The third heating vessel and fourth heating vessel separate a vaporphase from a liquid phase. The vapor phase is having entire remainingsolvent and free water therein. The liquid phase is having hydrocarbonswith limited solids, limited salts and alum therein. In next step, theliquid phase is centrifuged through a sixth centrifuge that is operatingat a predefined temperature for separating a product hydrocarbon layerfrom a water layer. The water layer is having limited salts, limitedsolids and alum therein. In next step, the water layer is treatedthrough a first reverse osmosis plant for obtaining water for use and areject stream. In next step, the vapor phase is condensed through athird condenser for obtaining water for use and solvent that can bereused in the high speed shear mixer. In next step, the water dominanthydrocarbon layer is heated in a fifth heating vessel for separatingvapors of solvent therefrom followed by condensing thereof in the thirdcondenser to obtain solvent for reuse and water for use. The fifthheating vessel produces a liquid phase that includes remaining water,limited hydrocarbons, salts and solids with a substantially lowturbidity. In next step, the liquid phase is treated in a settling tankfollowed by addition of a predefined amount of alum therein. Thesettling tank forms a water dominant alum layer and a gelatinous oilbearing layer.

In next step, the water dominant alum layer is filtered in a filtrationunit. The filtration unit separates the water dominant alum layer into afiltrate stream and a residual stream. The filtrate stream includeswater, alum and salts therein. The residual stream includes wet solidswith traces of hydrocarbons, salts and alum. The filtrate stream istreated in a second reverse osmosis plant for recovering usable watertherefrom. The filtration unit in accordance with the present inventionbrings down the turbidity value of the slop oil below 1 NTU.Effectiveness of filtration depends on pore size of the filtrate mediaand nature of hydrocarbons present in the slop oil.

In next step, the residual stream is mixed with the gelatinous oilbearing layer followed by drying thereof in a first hot dryer forobtaining a viscous liquid containing hydrocarbons, alum, solids andsalts. In next step, the viscous liquid is agitated in an agitator cumde-oiling unit by adding a predefined solvent followed by treatmentthereof through a seventh centrifuge thereby adding water therein. Theseventh centrifuge provides a water layer, a cake layer and a solventlayer, the water layer having alum, salts and limited solvent therein.The cake layer is preferably a cake of de-oiled solids with solvent,limited salts and limited alum. The water is treated in a sixth heatingvessel for obtaining vapors of solvent and water followed by treatmentthereof through a fourth condenser for obtaining solvent for reuse andwater either for use or for further treatment in said process. In nextstep, the solvent layer is treated in the fourth heating vessel forrecovery of solvent. In next step, the cake layer is treated in a secondhot dryer for recovery of solvent through the condenser. The second hotdryer produces dried de-oiled solids having traces of alum and saltstherein.

The third heating vessel is a multiple effect evaporator preferably withthermal vapor recompression adapted to avoid thermal cracking of theproduct hydrocarbon. The third heating vessel has a temperature in arange of about 70° C.-150° C. The fourth heating vessel has atemperature in a range of about 90° C. to 105° C. The fifth heatingvessel has a temperature in a range of about 90° C. to 105° C. The sixthcentrifuge is a hot centrifuge that has a temperature of about 80° C. to94° C. The sixth centrifuge is a hot settling tank that has atemperature of about 80° C. to 94° C. The hot settling tank may beoperated under high pressure so that operating temperature can beincreased to further reduce the viscosity of hydrocarbon that willfacilitate faster removal of free water without leading to boiling ofwater. The sixth heating vessel is an evaporator. The sixth heatingvessel has a temperature in a range of about 90° C. to 105° C.

The BTX study and Ash study help assists in determination of amount ofsolvent to be added in said process. The solvent is selected from thegroup of Benzene, Toluene, Xylene and other azeotropes of water. Thefirst hot dryer has a temperature of about 108° C. The second hot dryerhas a temperature of about 200° C. The first reverse osmosis plantremoves alum, salts and solids to produce water of usable quality.Addition of alum in the second settling tank neutralizes surface chargewhich facilitates speedy separation of the hydrocarbons throughflocculation and formation of the gelatinous oil bearing layer. Additionof alum in third settling tank when the slop oil is having turbiditybelow 90 NTU electrically discharge finest droplets of the hydrocarbonsand flocculate them thereby reducing turbidity by in a range of 90 wt.%-99 wt. %. Addition of alum is slow process by itself but it can bespeeded up by applying heat such that effectiveness of alum treatment isdependent on temperature and time.

The fourth centrifuge is a multi-pass centrifuge that reduces turbidityvalue of slop oil to a limiting value beyond which centrifuge is unableto produce any further value addition because then size variations ofdispersed oil droplets become narrow and population density of dispersedoil droplets also falls with increase in mean free path, residualdroplets are electrically charged and density difference is very small.The above lacuna for centrifuge gets magnified when starting turbidityvalue of the slop oil is very high. The solvent is added through thehigh shear mixer when centrifuge reaches its limiting value. Addition ofsolvent enhances the operating range of centrifuge by bringing in largevariation in droplet size and also by increasing the population densityof droplets along with increasing density difference between oil andwater. The centrifuge again reaches a limiting value at that point theresidual solvent is boiled out with free water in a temperature range ofabout 90° C. to 99° C.

In further alternative embodiment of the present invention, a processfor treatment of a sludge mixture comprising of a centrifuge isdisclosed. The process for treatment using only centrifuge comprises astep of centrifuging the sludge containing hydrocarbons, bound water,salts and solvents in a centrifuge to break the binding betweenhydrocarbons by increasing residence time of the hydrocarbons in thecentrifuge thereby forming three different layers, namely a viscoushydrocarbon layer with bound water, salts and solids, a free flowinghydrocarbons layer with limited salts and solids and a free water withlimited solids and salts. The centrifuge repositions the viscoushydrocarbon layer from a back side to a middle side of the centrifuge byslowly increasing revolutions per minute thereof and slowly decreasingan angle between a vertical axis of centrifuge container and ahorizontal plane thereof by gradually reducing but not allowing it tobecome 0°. The sludge mixture has bound water requiring furtherprocessing which reduces further processing cost and time. Thecentrifuge gives a large amount of marketable product hydrocarbons,namely free flowing hydrocarbons.

In yet another embodiment of the present invention, a process fortreatment of sludge mixture with combined effect of centrifuge andsolvent is disclosed wherein the sludge mixture contains bound water,salts and solids therein. The process for treatment comprises an initialstep of adding of a predefined amount of solvent in the sludge mixturefollowed by mixing thereof to reduce the viscosity of the sludgemixture. In next step, the sludge mixture is centrifuged in thecentrifuge to obtain a large layer of solvent and hydrocarbon, a layercontaining hydrocarbons and bound water and a free water layer. Thecentrifuge has an extended residence time for getting less of sludgewith bound water therein. The large layer of solvent and hydrocarbon istreated for recovery of solvent by boiling through free water in atemperature range of 90° C. to 99° C. at an atmospheric pressure. Thesludge mixture has bound water requiring further processing reducesthereby saving further processing cost and time. The centrifuge gives alarge amount of marketable product hydrocarbons, namely free flowinghydrocarbons.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a process flow diagram showing production and collection ofcrude at a group collection center;

FIG. 2 is a process flow diagram showing treatment of a sludge mixtureof FIG. 1 prior to removal of bound water therefrom;

FIG. 3 is a process flow diagram showing treatment of the sludge mixtureof FIG. 2 for removal of bound water therefrom;

FIG. 4 is a process flow diagram showing treatment of slop oil withhydrocarbon content above 10,000 PPM;

FIG. 5 is a process flow diagram showing treatment of the slop oil withhydrocarbon content equal to or less than 10,000 PPM;

FIG. 6 is a continued process flow diagram of FIG. 5 showing treatmentof the slop oil with hydrocarbon content equal or below 10,000 PPM;

FIG. 7 shows a graphical representation of Benzene at a rate of 2500 PPMwhen mixed with water using high shear mixer for 1 minute;

FIG. 8 shows a graphical representation of Benzene at a rate of 5000 PPMwhen mixed with water using high shear mixer for 1 minute;

FIG. 9 shows a graphical representation of Toluene at a rate of 2500 PPMwhen mixed with water using high shear mixer for 1 minute;

FIG. 10 shows a graphical representation of Toluene at a rate of 5000PPM when mixed with water using high shear mixer for 1 minute;

FIG. 11 shows a graphical representation of Xylene at a rate of 2500 PPMwhen mixed with water using high shear mixer for 1 minute;

FIG. 12 shows a graphical representation of Xylene at a rate of 5000 PPMwhen mixed with water using high shear mixer for 1 minute;

FIG. 13 shows a graphical representation of Coconut Oil at a rate of2500 PPM when mixed with water using high shear mixer for 1 minute;

FIG. 14 shows a graphical representation of Coconut Oil at a rate of5000 PPM when mixed with water using high shear mixer for 1 minute;

FIG. 15 shows a graphical representation of Coconut Oil at a rate of2500 PPM when mixed with water using high shear mixer for 3 minutes;

FIG. 16 shows a graphical representation of Coconut Oil at a rate of2500 PPM when mixed with water using high shear mixer for 5 minutes;

FIG. 17 shows a graphical representation of ONGC Oil at a rate of 2500PPM when mixed with water using high shear mixer for 1 minute;

FIG. 18 shows a graphical representation of ONGC Oil at a rate of 5000PPM when mixed with water using high shear mixer for 5 minutes;

FIG. 19 shows a graphical representation of ONGC Oil at a rate of 2500PPM when mixed with water using high shear mixer for 3 minutes;

FIG. 20 shows a graphical representation of ONGC Oil at a rate of 2500PPM when mixed with water using high shear mixer for 5 minutes; and

FIG. 21 shows a graphical representation of Diesel at a rate of 2500 PPMwhen mixed with water using high shear mixer for 5 minutes.

DETAILED DESCRIPTION OF THE INVENTION

The invention described herein is explained using specific exemplarydetails or better understanding. However, the invention disclosed can beworked on by a person skilled in the art without the use of thesespecific details.

References in the specification to “one embodiment” or “an embodiment”means that a particular feature, structure, characteristic, or functiondescribed in connection with the embodiment is included in at least oneembodiment of the invention. The appearances of the phrase “in oneembodiment” in various places in the specification are not necessarilyall referring to the same embodiment.

References in the specification to “preferred embodiment” means that aparticular feature, structure, characteristic, or function described indetail thereby omitting known constructions and functions for cleardescription of the present invention.

In the description and in the claims, the term “Sludge” is definedbroadly as a mixture of hydrocarbons, bound and unbound water, dissolvedand undissolved solids and naturally occurring emulsifiers. The sludgein accordance with the present invention is a sludge that contains totalwater content is in a range of 2 wt % to 95 wt %. However, when totalwater content is in a range of 2 wt % to 61 wt %, the entire water inthe hydrocarbons is bound water when emulsifiers are not additionallyadded. When the water content is above 61% the water is combination ofboth bound water and unbound water. Sludge is deadly pollutant as itcontains heavy metals and getting rid of is an expensive affair. It canpollute ground, water and even air through low volatiles.

In the description and in the claims, the term “Slop oil” is definedbroadly as a mixture of hydrocarbons, emulsifiers, un-dissolved solids,hydrocarbon coated un-dissolved solids and dissolved solids, bound andunbound water. The slop oil in accordance with the present invention ishaving hydrocarbon content in a range of 5 ppm-5 lac ppm. Thesehydrocarbons are not water soluble. Often when oil content extendsbeyond 10,000 PPM, it will reasonably quickly spilt into 3 layers, adecantable top layer of pure oil with PPM level of water, a significantwater bearing oil in the middle where separation rate of pure oil isslow and a residual bottom layer which is slop oil containing less than10,000 PPM.

In the description and in the claims, the term “Bound Water” is definedbroadly as water that does not come out hydrocarbon inspite centrifugingthe sludge at 21893 RCF for at least 10 minutes is bound water.

In the description and in the claims, the term “Unbound Water” isdefined broadly as any water apart from bound water.

In the description and in the claims, the term “Dissolved Solids” isdefined broadly as the solids that are dissolved in the water that comesout with sludge.

In the description and in the claims, the term “Un-dissolved Solids” isdefined broadly as the heavy metals including radioactive metals thatcome out from oil well along with crude.

Referring to FIG. 1, a process flow chart 100 shows a process undergoneby a petroleum crude 102 after being recovered through a plurality ofoil wells 101 followed by processing thereof at a group collectioncenter 104 (GCC, hereinafter) as illustrated. The crude 102 preferablycontains sulfur, bound water, unbound water, salts and solids. However,gases, if any, are removed from the crude 102 at line 101A before beingsent to GCC 104. The GCC 104 includes a desulfurization plant 106 thatseparates out sulfur from crude 102 via line 108 thereby forming asulfur-free crude stream 110 containing crude with bound water, unboundwater, salts and solids. The sulfur-free crude stream 110 is fed to agravity based settling tank 112. The gravity based settling tank 112separates crude into three streams namely an upper crude stream 114, amiddle crude stream 116 and a lower crude stream 118. The upper crudestream 114 contains crude with salts, limited solids and traces of waterthat follows line-A. The lower crude stream 118 contains water withsalts, solids and limited crude that follows line-B. It is understoodhere that lower crude stream 118 is slop oil stream having less than10,000 PPM hydrocarbon content in this one preferred embodiment. Themiddle crude stream 116 contains crude with salts, bound water, unboundwater and solids that is fed to a hot insulated settling tank 120through line 119.

The hot insulated settling tank 120 operates at an atmospheric pressureand at a temperature at about or less than 95° C. A de-emulsifier 122 isoptionally added to the hot insulating settling tank120 through line124.In addition, a high voltage oscillating electric field 125 is given tothe hot insulating settling tank 120 in this one embodiment. The hotinsulated settling tank 120 treats the middle crude stream 116 therebyforming three layers therein, namely a top crude layer 126, a middlecrude layer 128 and bottom, crude layer 130. The top crude layer 126contains crude with salts, limited solids and traces of water thatfollows line-A. The bottom crude layer 130 contains water with salts,solids and limited crude that follows line-B. In this one embodiment,the bottom crude layer 130 is slop oil having less than 10,000 PPMhydrocarbon content. In this one preferred embodiment, the middle crudelayer 128 is preferably sludge in accordance with the preferredembodiment which contains crude with bound water, salts, limited unboundwater and limited solids. Accordingly, the sludge 128 follows line-C inthis one preferred embodiment.

Referring to FIG. 2, a process 200 for treatment of the sludge 128before removal of bound water therefrom is illustrated. The sludge 128is fed to a first centrifuge 202 through the line-C. Additionally, aplurality of sludges 204 from all other sources with/without salts isadded to the first centrifuge 202 along with the sludge 128. The firstcentrifuge 202 is a batch type or multi-pass centrifuge, in this onepreferred embodiment. The first centrifuge 202 forms three layers,namely a top layer 208, a middle layer 206 and a bottom layer 210. Thebottom layer 210 preferably contains water with salts, solids andlimited crude. The middle layer 206 is preferably a viscous hydrocarbonlayer with bound water, limited solids and traces of unbound waterwith/without salts. The top layer 208 preferably contains free flowinghydrocarbons with or without salts, limited unbound water and limitedsolids. In this one embodiment, the bottom crude layer 210 is slop oilhaving less than 10,000 PPM hydrocarbon content.

The middle layer 206 is preferably fed to a first desalter 212 throughline 211 if it contains salts. A predefined amount of free water isadded to the first desalter 212 in order to obtain an upper stream 213and a lower stream 214. The lower stream 214 preferably contains waterwith salts, solids and limited crude which is mixed with bottom layer210 in this one embodiment. The upper stream 213 preferably containsdesalted viscous hydrocarbons with bound water, limited unbound waterand limited solids. The upper stream 213 follows line 213-A in this oneembodiment. Alternatively, the middle layer 206 can be directly fed to ahomogenizer 216 through line 215 if the middle layer 206 is withoutsalts and low volatiles. It is understood here that the line 215 may bemixed with the line 213-A before being fed to the homogenizer 216.

The top layer 208 is preferably fed to a third desalter 218 through line217 if it contains salts. A predefined amount of free water is added tothe third desalter 218 in order to obtain either two or three layers.The third desalter 218 produces an upper layer 220, a bottom layer 222and optionally a middle layer 224 if it has a fraction having boundwater contained therein. The upper layer 220 is a free flowing salt freehydrocarbon product with limited solids and traces of water. The bottomlayer 222 contains water with salts, solids and limited crude thatfollows line-B. In this one embodiment, the bottom crude layer 222 isslop oil having less than 10,000 PPM hydrocarbon content. The middlelayer 224, if formed, is added to the upper stream 213 in this oneembodiment.

The crude stream 114 containing crude with salts, limited solids andtraces of water following line-A (refer. FIG. 1) is fed to a seconddesalter 228. The second desalter 228 preferably forms three layers,namely a top layer 230, a middle layer 232 and a bottom layer 234. Thebottom layer 234 contains water with salts, solids and limited crudethat follows line-B. In this one embodiment, the bottom crude layer 234is slop oil having less than 10,000 PPM hydrocarbon content. The toplayer 230 is a desalted product crude with traces of solids and waterwhich goes back to, refinery as a product. The middle layer 232 containsdesalted viscous hydrocarbons with bound water that is added to thestream 213 and fed to the homogenizer 216.

The homogenizer 216 treats desalted viscous hydrocarbon layer with boundwater, limited unbound water and limited solids thereby adding a limitedsolvent stream 236 in case where the hydrocarbons are highly viscous.The homogenizer 216 advantageously facilitates addition of solvent onlyafter reducing volume of sludge and specifically for viscous hydrocarbonportion thereby drastically reducing overall use of solvent in theprocess. The solvent is also added to the homogenizer 216 in order tohelp assist in BTX study being performed during the process. The solvent236 also helps assists in reducing viscosity for removing bound water onaccount of viscosity. In this one preferred embodiment, the solvent 236is selected from one or more of the following Benzene, Toluene andXylene. The homogenizer 216 produces a non-viscous homogenized stream238 that follows line-D as illustrated. The stream 238 preferablycontains hydrocarbons that are volatiles free, desalted and non-viscous.The hydrocarbons in the non-viscous homogenized stream 238 preferablycontain bound water, limited unbound water and limited solids containedtherein.

Optionally, a heat based low volatiles stripping vessel 240 may beemployed if the desalted viscous hydrocarbons in the stream 213 containlow boiling volatiles therein. In such case, the stream 213 is sent to aheat based low volatiles stripping vessel 240 via line 242 instead ofbeing sent to homogenizer 216 via line 213-A. However, the viscoushydrocarbon layer 206 may be directly fed to the heat based lowvolatiles stripping vessel 240 through line 244 if it is free from saltsbut contains only low volatiles therein. The heat based low volatilesstripping vessel 240 is adapted in the process 200 to prevent the lowvolatiles to come out with solvent by separation thereof which wouldotherwise contaminate the solvent and removal of these hydrocarbonslater on would need fractional distillation which would be needlessly acostlier affair. Hence, the heat based low volatiles stripping vessel240 is adapted in the process to separate the low volatile hydrocarbons.The heat based low volatiles stripping vessel 240 is provided with awaste heat to facilitate heating. The heat based low volatiles strippingvessel 240 forms a vapor phase 246 and a liquid phase 248. The vaporphase 246 preferably contains vapors of low volatiles, hydrocarbons andwater. The liquid phase 248 preferably contains volatiles free, desaltedhot hydrocarbons with bound water, limited unbound water and limitedsolids.

The vapor phase 246 is sent to a first condenser 250 for removing heattherefrom followed by processing through a first condensate/phaseseparator 252. The condensate/phase separator 252 preferably forms afirst layer 254, a second layer 256 and a third layer 258. The firstlayer 254 contains pure water that can be reused in the process orpacked for sale. The second layer 256 contains low boiling liquidhydrocarbons that are mixed with a desalted product crude 230 throughline 260. The third layer 258 contains non condensable vapors ofhydrocarbons that are flared as a source of heat via line 262 asillustrated.

The liquid phase 248 is fed to a cooling vessel 264 wherein the hothydrocarbons are cooled to a room temperature and added to thehomogenizer 216 via line 266 to subsequently produce the product stream238 which follows line-D as illustrated.

It is understood here that, in case of typical sludge from ONGC lagoons,the first centrifuge 202 is able to separate sludge wherein one can finda small fraction of viscous hydrocarbons floating on the top carryingabout 40-44 wt % bound water and 13% Ash. The free flowing hydrocarbonsabout 40 wt % are obtained which contains 0.3 wt % to 0.8 wt % Ash andless than 3000 ppm of water. The water that goes out is having turbiditywell below 20 NTU. One cannot add this water back to the hydrocarbonsand make sludge thereby preventing reconstitution.

Referring to FIG. 3, a process 300 for treatment of the product stream238 for removal of bound water is illustrated. The product stream 238(refer FIG. 2) is fed to an agitator cum homogenizer 306 through theline-D after performing a BTX study 302 and an ash content study 304.The BTX study 302 is performed to detect moisture content in the productstream 238 and the ash content study 304 is performed to detect ashcontent in the product stream 238. A calculated amount of solvent 308 isadded in the agitator cum homogenizer 306 through line 310. It isunderstood here that the quantum of solvent added has an impact in theagitator cum homogenizer 308 in order to bring out the water at leasttemperature from the hydrocarbons. In case of Xylene being used assolvent, preferably, ratio of Xylene to wt. of hydrocarbon/water(whichever is higher) is 5.5. In case of Toluene being used as solvent,preferably, ratio of Toluene to wt. of hydrocarbon/water is 10.0. Incase of Benzene being used as solvent, preferably, ratio of Benzene towt. of hydrocarbon/water is 80.0.

In next step, the contents in the agitator cum homogenizer 306 are fedto a second centrifuge 312 through line 311. Optionally, the contents inthe agitator cum homogenizer 306 are fed to a hot insulating tank 312Athat separates out a water free top layer 312B containing solvent andhydrocarbons. The water free top layer 312B follows line-J as shown. Thesecond centrifuge 312 splits the contents in three layers, namely afirst layer 314, a second layer 316 and a third layer 318. The firstlayer 314 is an unbound water dominant hydrocarbon stream thatpreferably contains volatiles free desalted hydrocarbons, solvent,limited unbound water and solids contained therein. The second layer 316is a bound water dominant stream that preferably contains volatile freedesalted hydrocarbons with bound water, solvent, limited bound water andsolids contained therein. The third layer 318 preferably contains waterwith solids, limited hydrocarbons and solvent that follows line-B. It isunderstood here that the contents in the hot insulating tank 312A may bemixed with the third layer 318 via line 312C. In this one embodiment,the third layer 318 is slop oil having less than 10,000 PPM hydrocarboncontent.

It is understood here that in homogenizer 306 one puts hydrocarbons forthe treatment with up to 61% bound water wherein the difference indensity between water and hydrocarbon is in a region of 0.05 gm/cc andcontaining bound water which does not come out of the first centrifuge202 in spite of 21900 RCF for 10 minutes. However, after adding solvent308 followed by reduction in viscosity in the second centrifuge 312 theentire bound water comes out in subsequent processing. It is understoodhere that the same hydrocarbon had undergone similar centrifugal actionin first centrifuge 202 where viscosity was reduced still the boundwater that is recovered here had not come out. This fact of recovery ofbound water is a discovery in accordance with the present invention.

The first layer 314 is fed to a first heating vessel 320 through line322. The first heating vessel 320 operates at an atmospheric pressureand a temperature range of about 90° C. to 105° C., more preferably in arange of about 90° C.-98° C., in this one preferred embodiment. Apredefined amount of free water is added to the first heating vessel 320and waste heat is supplied for heating the first heating vessel at thedesired temperature in order to produce a first residual phase 324 and afirst vapor phase 326. In case where hydrocarbons have salt and/or ashor solids therein, then free water may perform an additional function ofde-salting and de-ashing apart from boiling out entire pure solvent forre-use or sale at temperatures below 100° C. The first vapor phase 326preferably contains vapors of entire remaining solvent and part ofunbound water which is fed to a second condenser 328 where heat isremoved from the vapors to form a liquid phase that moves to secondcondensate phase separator 330 through line 329. The condensate phaseseparator 330 separates the liquid phase into a solvent phase 332 and awater phase 334. The solvent phase 332 is preferably reused in theprocess. The water phase 334 is pure water having turbidity less than 5NTU which is either recycled in the process or packed for sale. Thefirst residual phase 324 preferably contains hydrocarbons and remainingunbound water with limited solids that is fed to a hot centrifuge/hotsettling tank 336. The hot centrifuge 336 operates at an atmosphericpressure and preferably at an inlet temperature less than or equal to95° C. and more preferably at the inlet temperature of 92° C.-93° C. Thehot centrifuge 336 preferably separates the liquid stream 324 into twolayers, namely a top layer 338 and a bottom layer 340. The top layer 338preferably contains volatiles free desalted hydrocarbon product withtraces of water/solids having water content less than 5000 ppm. Thebottom layer 340 entirely contains unbound water with solids and tracesof hydrocarbons. The bottom layer 340 is mixed with water phase 334 vialine 341 if it has turbidity less than 5 NTU. Alternatively, the bottomlayer 340 is fed to an alum based settling tank 342 via line 343 if theturbidity is greater than 5 NTU. The alum based settling tank treats thewater to bring the turbidity below 5 NTU followed mixing thereof withwater phase 334 via line 344. It is understood here that Alum basedsettling tank 342 may be a filtration unit or a reverse osmosis plant inother alternative embodiments of the present invention.

The second layer 316 is fed to a second heating vessel 346 through line348 that operates at an atmospheric pressure and preferably in atemperature ranges of about 70° C.-150° C. wherein waste heat is appliedfor heating purpose. However, it is understood that the second heatingvessel 346 may be a multi effect evaporator with thermal vaporrecompression alternative embodiment of the present invention. Also, itis understood that the second heating vessel 346 may be a foam breakerand entrainment suppressor in yet another embodiment of the presentinvention. A predefined of solvent may be added to the second layer 316if required. The second heating vessel 346 forms a second vapor phase350 and a second residual phase 352. The second vapor phase 350 containsvapors of solvent with entire bound water and unbound water which is fedand processed through the second condenser 328 as per the treatmentprocess of vapor phase 326 as stated above. The second residual phase352 is added the first heating vessel 320 and processed therethrough asillustrated.

Now referring again to FIGS. 1-3, in operation, the first centrifuge 202advantageously allows rapid separation of the sludge into value addedlayers at ambient temperature wherein typical CV of incoming sludge isabout 6,044 kcal/kg with water content about 40 wt. % and ash contentabout 3.68 wt. %. The first centrifuge substantially reduces the mass ofthe sludge to be handled subsequently by more than 3 times followed byseparating in-coming hydrocarbons into two fractions that commandsdifferent market price and in all probability different subsequenttreatment. Particularly, the first centrifuge 202 operates for 10minutes at relative centrifugal force (RCF, hereinafter) of 4,500 (whichrequires cycle time of 30 mins.) to produce about 41 wt. % of the freeflowing hydrocarbon layer 220 with 3,864 ppm water and 0.88 wt. % ashhaving CV of 10,635 kcal/kg, about 32 wt % of the viscous hydrocarbonlayer 206 having 42.21 wt. % water and 8.61 wt. % ash with CV of 5,210kcal/kg, and 26 wt. % of the slop oil after subsequent treatment withAlum having less than 20 NTU turbidity.

In operation, the first centrifuge 202 enhances force of buoyancy overextended time by gradually increasing the RPM and also by havingcentrifuge bottles held onto rotor through a pivot. The first centrifuge202 provides an extended residence time with enhanced force of buoyancythat allows building up of an adequately large Kinetic Energydifferential between droplets of separating liquids, which then, onexceeding a threshold value, provides the energy needed to break thebonds that were holding these droplets together. Breaking of bonds wasnecessary but not adequate. Subsequently, these different materials arecarried as entirely as possible through one another and collect theminto distinct, single component layers 206, 208 and 210. The enhanced orincreased residence time or centrifugal force squeezes out more waterand to a small extent even oil from viscous layer 213 and by doing somakes it even further viscous and hence reaching a limiting point beyondwhich it did not make sense to try any further. The Combination ofprogressively increasing RPM and of pivots holding centrifuge bottlesprobably had a couple of additional impacts. Initially, a less RPM whichis low centrifugal force limits accumulation of viscous hydrocarbonsthat helps in collection of the viscous hydrocarbons as lumps withoutflattening thereof as cakes. Further, a low RPM wherein the force ofweight is larger than centrifugal force helps collection of the viscoushydrocarbons at the bottom-most space within bottles thereby leavingbehind ample free space at top. This helps initially released weaklybound water to reach the extreme end and then collect behind theselumps. The viscous hydrocarbons preferably grow with time as additionalmaterial accreted. Subsequently, more water releases and collects behindviscous lumps from top thereby releasing them from the base of thebottle and then slowly moving them towards their final position in thecentre. Further, when RPM rises, the force of buoyancy increases toswivel out the bottles progressively by reducing their angle withhorizontal and with that above described process became more vivid.Eventually, these bottles become near horizontal but never completelyhorizontal. At the end, there will be some small residual angle with thehorizontal. Eventually the centrifuge 202 allows the viscous hydrocarbonto get flattened with time and high centrifugal force into thick discshaped layer. But even then since these bottles are never trulyhorizontal this disc has a limited contact with bottle surface at itstopmost point which provides a relatively easy opening for water topenetrate in and collect behind it.

In operation, the three. desalters 212, 218, 228 facilitate de-saltingof crude prior to removing bound water and also prior to dispatching itto refineries. This has a special importance in accordance with thepresent invention. The process 200 includes placement of desalters 212,218 and 228 allow crude de-salting at the specific location within theproposed process which is different from its current location. Thedesalters 212, 218 and 228 prevent needless, expensive, time-cum-capitalconsuming repetition of crude de-Watering at refineries, after firstcarrying out exactly similar process earlier at GCCs. Besides, thedesalters 212, 218 and 228 enhance product quality and reduce expense onpaid energy, by preventing ingression of water into crude stream atrefineries. This in turn reduces or eliminates sludge accumulation indown-stream product supply chain. The desalters 212, 218 and 228 at ourdisclosed location of the process 200 facilitates mitigation of theproblem of bound water that gets into Crude while de-salting, withouthaving the advantage of distillation column. The desalters 212, 218 and228 prevent mixing of hydrocarbons having bound water with hydrocarbonshaving unbound water and the product hydrocarbon stream in comparison tomere de-salting. This also allows preventing mixing of viscoushydrocarbons with free flowing hydrocarbons. The second desalter 228 hasunique ability to dispatch de-salted hydrocarbons to refineries withoutloading them with bound water.

In operation, the heat based low volatiles stripping vessel 240facilitate stripping in case of hydrocarbons coming in with bound waterand low-boiling volatiles. The stripping vessel 240 strip these lowvolatiles and separate them by heating prior to removal of bound waterusing solvents and even prior to addition of solvent itself in theprocess 200 thereby preventing the low boiling volatiles to distill outwith the solvent during removal of bound water with solvent indownstream of the process 200 wherein depending on the solvent used thefinal temperature could rise at least as high as 140° C. The strippingvessel 240 also prevents the low volatiles to enter in subsequentpurification of the solvent which would otherwise become a far moreexpensive & elaborate a process. Further, the heat based low volatilesstripping vessel 240 prevents low boiling volatiles to distill out withthe solvent during removal of bound water subsequently with the use ofsolvent in the homogenizer 306 and the second centrifuge 312 followed byexposure to temperature of at least as high as 98° C. in the firstheating vessel 320. The heat based stripping vessel facilitates recoveryof the low boiling hydrocarbons that can be recycled back to thedesalted product crude 230 which apart from conservation and economicaladvantages help to deliver back the hydrocarbons in as original form aspossible. If a fraction of low volatiles becomes non-condensable stream258 due to thermal cracking then that fraction would be either flared orcombusted to provide an additional source of heat.

Moreover, addition of solvent before the second centrifuge 312 is moreimportant instead of addition of solvent, before the first centrifuge202. This is partly because one would end up consuming more solvent insuch case as it will get needlessly mixed also with the free flowinghydrocarbons. This may lead to an additional cost and process forsubsequent removal of the solvent from free flowing hydrocarbons.Moreover, the removed solvents would get contaminated with low boilinghydrocarbons in such case. Also, one would end up mixing low valuedviscous hydrocarbons with higher valued free flowing hydrocarbons insuch case.

In operation, the second centrifuge 312 treats the solvent bearingsludge after removing the clear water with turbidity values from below20 NTU in certain cases. The second centrifuge 312 removes entireremaining bound water from the sludge stream fed thereto such as FurnaceOil Sludge, ONGC Viscous Hydrocarbons and the like. The secondcentrifuge 312 does not remove the entire bound water from the sludgewhere a part of hydrocarbons holds onto bound water on account ofemulsifier. Apart from removing bound water, the second centrifuge alsohelps in reducing ash in hydrocarbons.

However, it is understood here that mere use of the second centrifuge312 alone and without solvent could not remove traces of bound waterinspite of high residence time of 10 minutes at an RCF value as high as21,900 because of high drag on account of high viscosity. The use ofsolvent stream 308 is extremely important to reduce viscosity and tomake the centrifuge 312 effective when used subsequently. On the otherhand, solvent by itself is more effective than the centrifuge 312 butstill it fails to remove entire bound water inspite of 72 hours ofresidence time as part of the water is tightly held by hydrocarbons.Bound water could not be separated either by the use of solvent alone,even when heated to temperatures a little below their azeotropic boilingtemperature or by the use of centrifuge alone.

Accordingly, combined use of solvent stream 308 with second centrifuge312 to separate bound water completely and quickly at ambienttemperatures from the viscous sludges is extremely important inaccordance with the present invention. The process 300 combines theenhanced force of buoyancy due to increased acceleration due to gravityand additionally a significant decrease in viscosity of the sludge byusing the solvent, like Xylene, that is in proportion of two times theweight of sludge itself at ambient temperatures and over an extendedperiod of time thereby affecting complete separation of bound water fromviscous hydrocarbons which is hitherto not possible either by singlyusing even 4.87 times more powerful a centrifuge over same time alone orby singly using the same solvent in similar proportion even at twice theambient temperature Over 72 hours as against 10 minutes.

Referring to FIG. 4, a process 400 for pretreatment of the slop oil inaccordance with an alternative embodiment of the present invention isshown. The slop oil stream 402 has hydrocarbon content greater than10,000 PPM. In this one alternative embodiment, the slop oil feed stream402 preferably contains water with salts, solids and limitedhydrocarbons with or without bound water. The slop oil feed stream 402is sent to a first settling tank or a phase separation column 404wherein preferably three layers are formed, namely a top layer 406, amiddle layer 408 and a bottom layer 410. The top layer 406 preferablycontains free flowing hydrocarbons with or without salt along withtraces of water and solids. The middle layer 408 preferably containshydrocarbons with large amounts of water with or without salts andsolids. The bottom layer 410 preferably contains water with salts,solids, limited hydrocarbons which follows line-B. In this onealternative embodiment, the bottom layer 410 is slop oil having lessthan 10,000 PPM hydrocarbon content. The top layer 406 is directlystored as a product storage tank 412 through line 411 if it does notcontain any traces of salts therein. Alternatively, the top layer 406may be optionally fed to third desalter 218 (refer FIG. 2) via line F ifit contains salts therein. The middle layer 408 is fed to a secondsettling tank 414 followed by adding a predefined amount of alum.

The second settling tank 414 forms a first layer 416, a second layer 418and a third layer 420. The first layer 416 preferably contains freeflowing hydrocarbons with or without salts and traces of water andsolids which is mixed with the top layer 406 in this one embodiment. Thesecond layer 418 mainly contains alum with water having salts, solids,limited hydrocarbons. The second layer 418 is mixed with the bottomlayer 410 to follow line-B as illustrated. The third layer 420 is agelatinous oil bearing layer containing hydrocarbons, alum, salts,solids and water contained therein. The third layer 420 follows line-H.It is understood here that addition of alum in the second settling tank414 facilitates speedy separation of the hydrocarbon through coagulationand formation of the gelatinous oil bearing layer.

The first settling tank 404 may occasionally produce a fraction 422which may contain viscous hydrocarbons with or withoutsalts/solids/bound water. The fraction 422 may be optionally fed to afirst desalter 212 via line-I if it contains salts and bound water both.The fraction 422 may be optionally fed to second desalter 228 by mixingwith line-A if it contains salts without any bound water therein. Thefraction 422 may be optionally mixed with an upper stream 213 via line-Eif it contains only bound water without any salts therein. The fraction422 may be optionally sent to a third centrifuge 424 via line 423 if itcontains only solids without any salts and bound water therein. Apredefined amount of solvent is added to the third centrifuge 424 inorder to separate the fraction 422 into two layers, namely a top layer426 and a bottom layer 428. The third centrifuge 424 reduces drag,surface charge on the particles of hydrocarbon thereby reducing meanfree path and allowing coalescence of the particles at ambienttemperature. The top layer 426 preferably contains hydrocarbons andsolvent with traces of solids which is sent to the first heating vessel320 via line-J. The bottom layer 428 preferably contains solids that arecoated with hydrocarbons which follows line-K in this one embodiment.However, the bottom layer 422 may be directly stored as a product 430via line 429 if it is free from salts, solids and bound water.

Referring to FIGS. 5-6, a process 500 for treatment of the slop oilfollowing line-B in accordance with the present invention is shown. Theslop oil stream 502 preferably has a high turbidity and hydrocarboncontent less than 10,000 PPM. In this one embodiment, the slop oilstream 502 preferably contains water with salts, solids and limitedhydrocarbons with or without bound water. The slop oil feed stream 502is fed to a fourth centrifuge 504 to reduce turbidity and obtain astream 506 having low turbidity. The fourth centrifuge 504 is amultipass centrifuge that works on its own as long as population densityof ultrafine particles of hydrocarbons is high because then mean freepath is low. Because, ultrafine particles can be removed only after theycoalesce and for coalescing there has to be relative movement betweenparticles. This comes only due to relative particle size distribution.This distribution is very narrow in the zone of high density of smallparticles. It is understood here that the multipass centrifuge 504 mustbegin with fresh slop oil. Also, it is understood that the gap betweenslop oil generation and operation of centrifuge 504 should be as minimumas possible. Further, it is understood that the fourth centrifuge 504uses the relative motion brought by high G till such time that mean freepath between the hydrocarbon particles is increased beyond maximumcapacity thereof.

The stream 506 having low turbidity is fed to a high speed shear mixer508 wherein a predefined amount of solvent is added via line 510 therebyforming a mixture 512 that is fed to a fifth centrifuge 514. Addition ofsolvent followed by high shear mixing, in a range of about 8000-10000RPM, allows formation of the adequate size solvent particles, preferablyin a range of about 0.5 to 0.8 micron size whose population densityincreases by a substantial amount. It is understood that for adequatedisintegration of solvent there is an optimum mixing time that is about1 min. Further increase in time may result in increase in particle sizeand fall in turbidity. The right particle size of solvent preferablyremoves almost similar size of ultra fine oil particles. Thereafter thecoalescence speed increases which prove to be a rate controlling step inaccordance with the present invention wherein effect of coalescenceextends in the working range of the fifth centrifuge 514. Thereafter,the centrifuge 514 starts working due to high population density andcontinues till the population density falls down to an earlier level.This effectively allows the oil particles to completely go out.Moreover, addition of solvent facilitates coalescence that enhances theefficiency of the centrifuge 514 by having enhanced sweeping effectwherein a limiting factor for centrifuge 514 about population density ofultra fine droplets is reached with solvent droplets instead of oildroplets.

Addition of solvent in the high speed shear mixer 508 enhancespopulation density within the slop oil that makes the fifth centrifuge514 to efficiently allow the solvent to facilitate coagulation therebymoving the hydrocarbon particles to move from bottom and separate with aswiping impact. Addition of solvent in large amount in the high speedshear mixer 508 allows replacement of hydrocarbon droplet with solventdroplet for replacing oil with solvent therein.

The fifth centrifuge 514 preferably forms two layers, namely a top layer516 and a bottom layer 518. The top layer 516 is a solvent dominanthydrocarbon layer that preferably contains a top layer comprisingsolvent, hydrocarbons with or without bound water, limited free water,limited salts and limited solids. The bottom layer 518 is a waterdominant hydrocarbon layer that preferably contains water, limitedsolvent, limited hydrocarbons, salts, solids with very high turbidityvalue.

The top layer 516 is subjected to a BTX study 520 to know water and ashcontent for deciding requirement of solvent, if needed. The top layer516 is added to a third heating vessel 522 via line 524 if the top layer516 contains hydrocarbons having bound water contained therein.Alternatively, the top layer 516 is added to a fourth heating vessel 526through line 528 if the top layer 516 contains hydrocarbons having nobound water contained therein. The third heating vessel 522 may be amulti effect evaporator with thermal vapor recompression, foam breakerand entrainment suppressor in other alternative embodiments of thepresent invention. The third heating vessel 522 preferably operates atan atmospheric pressure and in a temperature range of about 70° C.-150°C. in this one embodiment. A predefined amount of additional solvent maybe added to the third heating vessel 522 based on the BTX study 520. Apredefined amount of waste heat is applied to the third heating vesselfor increasing the temperature of the third heating vessel 522 andforming two phases, namely a vapor phase 530 and a liquid phase 532. Theliquid phase 532 preferably contains hydrocarbons, remaining solvent,limited solids and limited salts therein. The vapor phase 530 containsvapors having a part of solvent, entire bound water and free watertherein. The vapor phase 530 is fed to a condenser 536 through line 538.The condenser 536 removes heat from the vapor phase 530 followed byprocessing through a condensate/phase separator 540. Thecondensate/phase separator 540 preferably forms a first layer 542 and asecond layer 544. The first layer 542 contains pure water that can bereused in the process or packed for sale. The second layer 544 containssolvent that is reused in the process by mixing with the solvent line510. The liquid phase 532 is free from bound water which is subsequentlyadded to the fourth heating vessel 526 through line 534. The fourthheating vessel 526 operates at an atmospheric pressure and in atemperature range of about 90° C. to 105° C. A predefined amount of asolvent stream-G (refer FIG. 6) may be added to the fourth heatingvessel 526 as illustrated. The heating vessel 526 produces a vapor phase546 and a liquid phase 548. The vapor phase 546 contains entireremaining solvent and a part of free water. The liquid phase 548contains hydrocarbons, remaining free water, limited solids, limitedsalts and alum. The vapor phase 546 is added to the condenser 536 vialine 550. The liquid phase 548 is fed to a sixth centrifuge 552. Thesixth centrifuge 552 is a hot centrifuge or hot settling tank in thisone embodiment that operates at an atmospheric pressure and at atemperature equal to or less than 95° C. The sixth centrifuge 552preferably produces two layers, namely a top layer 554 and a bottomlayer 556. The top layer 554 is a hydrocarbon product having traces ofwater, salts and solids therein. The top layer 554 is stored or packedfor sale. The bottom layer 556 contains water, limited salts, limitedsolids and alum. The bottom layer 556 is processed through a RO plant558 to obtain a pure water stream 560 and a reject stream 562. The purewater stream 560 is mixed with the first layer 542. The reject stream562 follows line-H in this one embodiment.

The bottom layer 518 is fed to a fifth heating vessel 564 that operatesat an atmospheric pressure and in a temperature range of about 90° C. to105° C. The fifth heating vessel 564 is supplied with waste heat toachieve the desired temperature range. The fifth heating vessel 564produces a vapor phase 566 and a liquid phase 568. The vapor phase 566preferably contains vapors of solvent and part of water that is furtherprocessed through the condenser 536 as illustrated. The liquid phase 568preferably contains remaining water, limited hydrocarbons, salts andsolids. The liquid phase 568 has substantially low turbidity whichfollows line-E as illustrated.

As shown in FIG. 6, the liquid phase 568 following line-E is fed to athird settling tank 602 wherein a predefined amount of alum stream 604is added. The alum stream 604 is preferably added to reduce theturbidity of the liquid phase 568 and bring it down below 2.0 NTU. Thethird settling tank 602 may be optionally provided with heat tofacilitate alum treatment in hot condition. Addition of Alum underheated condition at a temperature in a range of about 80° C. to 90° C.for at least four hours may reduce the turbidity of the slop oil by atleast 90%. Addition of the alum stream 604 is more effective underheating that allows wider distribution pattern of droplets that firstlyallows the oil particles to attach with each other and form a gel. It isunderstood here that efficacy of addition of alum stream 604 is notlimited by availability of ions as is a kinetics related problem. Thesettling tank 602 preferably forms two layers, namely a top layer 606and a bottom layer 608. The top layer 606 is a water dominant alum layerthat preferably contains water, alum, solids, salts and traces ofhydrocarbons contained therein. The bottom layer 608 is preferably agelatinous oil bearing layer containing hydrocarbons, alum, water,solids and salts therein. However, it is understood here that the scummay be collected either at top or both at the top and bottom dependingupon the ppm level in other alternative embodiments of the presentinvention. The top layer 606 is sent to a filtration unit 610 thatsplits the top layer 606 into a filtrate stream 612 and a residualstream 614. The residual stream 614 preferably contains solids withtraces of hydrocarbons, salts and alum. The residual stream 614 is mixedwith the bottom layer 608 through line 616. The filtrate stream 612preferably contains water, alum and salts. The filtrate stream 612 issent to a RO plant 618 through line 617 for obtaining a pure waterstream 620 if total dissolved solids (TDS, hereinafter) of the filtratestream 612 is high else directly stored or packed for sale via stream622if the TDS is low. It is understood here that addition of alum in thirdsettling tank 602 improves rate of filtration in the filtration unit 610thereby substantially reducing turbidity below 2 NTU. The bottom layer608 is mixed with the third layer 420 (refer FIG. 4) following line-Hand sent to a first hot dryer 624. The first hot dryer 624 preferablyoperates at an atmospheric pressure and a temperature of about 108° C.which boils out the water in form of a water vapor stream 626 therebyretaining a viscous liquid stream 628 containing hydrocarbons, alum,solids and salts. The viscous liquid stream 628 is fed to anagitator/de-oiling unit 630. A predefined amount of solvent stream 631is added to the agitator/de-oiling unit 630 along with the bottom layer428 (refer FIG. 4) following line-K and containing solids that arecoated with hydrocarbons. The agitator/de-oiling unit 630 produces freeflowing liquid stream 632 that preferably contains solvent withhydrocarbons, alum, salts and de-oiled solids. The free flowing liquidstream 632 is sent to a seventh centrifuge 634 through line 633. It isunderstood however that the seventh centrifuge 634 may be phaseseparator in other alternative embodiments of the present invention. Theseventh centrifuge 634 preferably produces three layers, namely a firstlayer 636, a second layer 638 and a third layer 640. The first layer 636preferably contains solvent and hydrocarbons which is added to theheating vessel 526 (as shown in FIG. 5) through line-G. The second layer638 is a water dominant alum layer that preferably contains water withalum and salts along with limited solvent. The second layer 638 is fedto a sixth heating vessel 642 which operates at an atmospheric pressureand in a temperature range of about 90° C. to 105° C. The sixth heatingvessel 642 produces two phases namely, a vapor phase 643 and a liquidphase 644. The liquid phase 644 preferably contains water, alum andsalts contained therein. The liquid phase 644 is recycled to the ROplant 618 via recycle line 646. The vapor phase 643 preferably containsvapors of solvent and water. The vapor phase 643 is sent to a condenser648 for removing heat followed by processing through a condensate/phaseseparator 650. The condensate/phase separator 650 preferably forms afirst layer 652 and a second layer 654. The first layer 652 containspure water that can be reused in the process or packed for sale. Thesecond layer 654 contains solvent that can be reused in the process. Thethird layer 640 preferably contains cake of wet de-oiled solids withsolvent, limited salts and limited alum. The third layer 640 is sent toa second hot drier 656 that operates at an atmospheric pressure andtemperature of about 200° C. A predefined amount of waste heat isapplied to the dryer 656 to achieve desired temperature. The second hotdryer 656 treats the third layer 640 thereby removing a vapor stream 658thereby forming a residual stream 660. The vapor stream 658 preferablycontains vapors of solvent and water contained therein. The residualstream 660 preferably contains dried de-oiled solids with traces of alumand salts. The vapor stream 658 is mixed with the vapor phase 643 andfurther treated through the condenser 648 as illustrated.

Referring now to FIGS. 4-6, in operation, the processes 400 and 500advantageously convert pollutants into valuable product streams therebymitigating problems of environmental pollution and damage toenvironment. In addition, the processes 400 and 500 facilitate bestpossible recovery of oil and valuable water wherein the water can beused as a drinking water for commercial use at a cost less than the costof storage of sludge/slop oil. The processes 400 and 500 facilitate useof chemicals for recovery of oils such that the chemicals used aretotally recycled and reused in the process. Further, the process of thepresent invention runs at almost nil energy cost by making use of wasteheat in overall process.

EXAMPLES

The following examples and comparative examples are provided todemonstrate particular embodiments of the present invention. It shouldbe appreciated by those skill in the art that the methods disclosed inthe examples and comparative examples that follow merely representexemplary embodiments of the present invention. Those of skill in theart should, in light of the present disclosure, appreciate that manychanges can be made in the specific embodiments described and stillobtain a like or similar result without departing from the spirit andscope of the present invention.

Example-1

TABLE 1.1 DESCRIPTION OF OILS USED IN LAB SI. FURNACE No. DESCRIPTIONOIL DIESEL 1 Wt. % Water in Hydrocarbons as 0.21 0.01 per BTX 2Calorific Value of Oil (kcal/kg) 10,173 11,002 3 Wt. % Ash in Oil 0.230.00

TABLE 1.2 PREPARATION OF FURNACE OIL SLUDGE Wt. % CV OF TURBIDITY BOUNDSLUDGE Wt. % OIL IN OF WT. % Wt. % Wt. % Wt. % WATER WITH SLOP SLOP SLOPLOSS Sludge WATER SLS SLUDGE IN BOUND OIL OIL IN OIL OF No. USED USEDFORMED SLUDGE WATER FORMED PPM (NTU) MATERIAL 1 2.02 0.00 100.00 2.159,960 0.00 0.00 0.00 0.00 2 10.01 0.00 100.00 9.91 9,148 0.00 0.00 0.000.00 3 15.08 0.00 100.00 14.84 8,640 0.00 0.00 0.00 0.00 4 35.00 0.00100.00 34.65 6,590 0.00 0.00 0.00 0.00 5 47.52 2.51 63.11 19.02 8,13432.92 464 959 3.97 6 48.53 2.44 57.90 18.92 8,142 38.59 16,740 >10,0003.50 7 50.01 0.00 100.00 49.94 5,146 0.00 0.00 0.00 0.00 8 60.79 0.00100.00 59.48 4,109 0.00 0.00 0.00 0.00 9 69.97 0.00 52.90 43.84 5,79840.31 2,144 2,535 6.79 10 82.60 0.00 31.50 44.77 5,610 67.95 930 1,0800.55 11 96.44 0.00 5.92 39.78 6,130 93.52 2,110 2,583 0.57

TABLE 1.3 PREPARATION OF DIESEL SLUDGE PPM Wt. % CV OF OF BOUND SLUDGEWt. % OIL Wt. % Wt. % Wt. % WATER WITH SLOP IN TURBIDITY WT. % SI. WATERSLS SLUDGE IN BOUND OIL SLOP OF SLOP LOSS OF No. USED USED FORMED SLUDGEWATER FORMED OIL OIL (NTU) MATERIAL 1 50.00 0.00 0.00 — — 100.005,00,000 >10,000 0.00 2 48.85 2.43 45.18 6.44 10,160 49.791,43,656 >10,000 5.02

Preparation of Sludges/Emulsions for Subsequent Removal of Bound andFree Water

A predefined amount of in-house Sludge was prepared with water usingViscous/Non-Viscous Hydrocarbons in order to understand sludges and alsofor subsequent removal of entire Bound Water from therein. Accordingly,weighed amounts of Water, Hydrocarbons and Sodium Lauryl Sulphate asemulsifier, if any, are mixed and then stirred at 10,000 rpm using ahigh shear Mixer, for 1 minute at a time and for 5 times, while ensuringthat temperature of mixed material never exceeded 58° C. After every 1minute of mixing the material was cooled to near ambient temperature.Subsequently, a representative sample was subjected to 10 minutes ofcontinuous centrifuging at 21,893 relative centrifugal force (RCF), in abatch type centrifuge, to find out if any water separated. If yes, thenit was considered as slop oil. The remaining material was considered assludge with bound water. Different types of sludges were prepared asshown in the following table 1.2 and table 1.3.

It was understood that the sludge with bound water mean from wherein nofree water visibly emerges out even on batch centrifuging it at RCF of21,893 with residence time of 10 minutes at peak RCF. The sludges weremade without using external emulsifier like Sodium Lauryl Sulphate (SLS)with viscous Furnace Oil but not with free flowing diesel. It, wasobserved that, drag on account of viscosity was an important reason forhydrocarbons to tightly hold onto fine droplets of water. It wasobserved that for diesel, use of Sodium Lauryl Sulphate was necessary.Even then, as can be seen from Table #3, only 5.96 wt. % of total waterpresent could be bound to diesel and 82.64 wt. % of diesel could bebound to water, thereby forming 45.18 wt. % Sludge, when using 2.43 wt.% SLS. It was also observed that sludges could be prepared using SLS,both with Furnace Oil and Diesel. However, with same amount of water,the quantum of diesel sludge with bound water was nearly half of thatone got with furnace oil. It was further observed that water holdingability of Furnace Oil in sludge was deteriorated sharply with thepresence of SLS. This was because with the use of SLS, sludge became farless viscous. This also showed that binding between hydrocarbons andwater on accounts of viscosity and the use of SLS did not add up. Inother words, their contributions towards binding the two were notadditive. Further, it was observed that with use of SLS, the quantum ofsludge with bound water dropped down. This was because now only aquarter of water was present that participated in binding with furnaceoil. However, it was observed that the strength of binding was a lotstronger than what would have been possible in the absence of SLS. Itwas observed from Table 1.2 that, in Sludge No. 5, SLS was added to thewater prior to production of sludge. While in Sludge No. 6, SLS wasadded to a sludge that had already been prepared with 49.75 wt. % water.From this Table it was observed that the binding between water andhydrocarbon was slightly stronger when SLS was uniformly dissolved inwater prior to production of the sludge. It was observed that there wasan upper limit on how much bound water can be held onto by Furnace Oilon account of its viscosity wherein the furnace oil, cannot be made tohold the entire water as bound water through vigorous mixing beyondabout 1.5 times of its own weight of water as can be clearly seen intable-2. Further, it was observed that furnace oil can hold water asbound water only up to 67 to 82% of its own weight beyond a thresholdvalue. Also, the quantum of sludge formed with bound water was found tobe decreased sharply with increasing water content. It was observed thatthe remaining water stayed as free water with traces of hydrocarbons init. That was called slop oil. Though was difficult to produce freshSludge with more than 60-62 wt. % bound water in it, using furnace oil,through mixing, but then one can always retain the Furnace Oil Sludgewith more than 80 wt. % bound water in it, by removing a part of Furnaceoil from an already prepared sludge, using a solvent with centrifuge, ascan be seen later in Samples 2 to 4 in later Table 4.3. Finally, it wasobserved from the calorific values of sludges deteriorate in proportionwith water content therein.

Example-2 Pre-Treatment of Incoming Sludges/Emulsions with Centrifuge

It was an aim to determine extent of bound water present in an incomingsludge thereby splitting it into sludge with bound water and slop oilthrough Centrifuge. Also, it was an aim to establish that with a batchCentrifuge alone it is possible to recover value added, marketablehydrocarbons; remove a part of water present and also reduce the quantumof Sludge that would require further treatment. Accordingly, the Sludgesprepared in house and also Lagoon Sludge procured from Oil and NaturalGas Corporation (ONGC) of India were treated in a Batch Type Centrifugeat RCF of 4,500 and 21,893 with varying residence time therebyseparating and weighing the fractions thereafter followed by doing massbalance for the material centrifuged. Further, these fractions wereevaluated for their moisture content by a BTX Process followed by ashcontent by heating in a muffle furnace and subsequently for calorificvalues using bomb calorimeter and turbidity of Free Water that came out,with Hach Turbidity Meter. The constituents in the prepared sludge andthe conditions under which these Sludges were centrifuged are mentionedin accordance with below mentioned tables 2.1-2.8.

TABLE 2.1 CONSTITUENTS IN FURNACE OIL SLUDGE SAMPLES Sludge SludgeSludge Sludge Sludge with SI. with 47.5 Wt. % with 50 Wt. % with 70 Wt.% with 83 Wt. % 96 Wt. % No. DESCRIPTION Water Water Water Water Water 1Wt. of Water taken 355.43 500.06 350.10 419.35 1,431.82 in High Shearmixer in (g) 2 Wt. of Sodium 18.75 0.00 0.00 0.00 0.00 Lauryl Sulphateadded as Emulsifier in above Water (g) 3 Wt. of Furnace Oil 374.09500.13 150.27 88.33 52.91 added to above Water (g) 4 Total Wt. of Sludge748.27 1,000.19 500.37 507.68 1,484.73 Sample (g) 5 Wt. % Water in 46.8549.46 69.55 82.02 95.79 above Sludge Sample as determined by BTX 6Calorific Value in 5,260 5,148 3,135 1,736 320 kcal/kg

TABLE 2.2 CENTRIFUGING DETAILS Sludge Sludge Sludge Sludge Sludge SI.with 47.5 Wt. % with 50 Wt. % with 70 Wt. % with 83 Wt. % with 96 Wt. %No. DESCRIPTION Water Water Water Water Water 1 Time taken in mints toReach 2.60 2.55 2.95 2.80 2.68 Max. Relative Centrifugal Force 2 Max.Relative Centrifugal 21,893 21,893 21,893 21,893 21,893 Force at theCentrifuge was operated 3 Holding Time at Max. Relative 10 10 10 10 10Centrifugal Force in minutes 4 Time taken to come back to 16.55 16.8016.50 16.50 16.50 zero Relative Centrifugal Force 5 Total Residence Timein min. 29.15 29.35 29.45 29.30 29.18 inside centrifuge

TABLE 2.3 RESULTS OF PRE-TREATMENT OF FURNACE OIL SLUDGE SAMPLES INCENTRIFUGE Sludge Sludge Sludge Sludge Sludge SI. with 47.5 Wt. % with50 Wt. % with 70 Wt. % with 83 Wt. % with 96 Wt. % No. DESCRIPTION WaterWater Water Water Water 1 Wt. % Sludge recovered 63.11 97.82 52.90 31.505.92 having Bound Water therein 2 Wt. % Bound Water in above 19.02 49.5143.84 44.77 39.78 Sludge as determined by BTX 3 Calorific Value ofSludge 8,134 5,146 5,798 5,610 6,130 with Bound Water (kcal/kg) 4 Wt. %Slop Oil that 32.92 0.00 40.31 67.95 93.52 Separated Out from abovePrepared Sludge 5 Oil Content in Slop Oil 464.00 — 2,144 930 2,110 (PPM)6 Turbidity of Slop Oil (NTU) 959 — 2,535 1,080 2,583 7 Wt. % Oil lostthrough 0.43 0.83 0.23 0.00 0.00 adhering to Various Surfaces 8 Wt. %Water lost through 3.54 1.35 6.56 0.55 0.56 Evaporation and Wetting ofSurfaces

Diesel Based Sludges

TABLE 2.4 CONSTITUENTS IN DIESEL SLUDGE SAMPLES SI. No. DESCRIPTION Test1 Test 2 Test 3 1 Wt. of Water taken in High 302.11 301.84 300.11 Shearmixer in (g) 2 Wt. of Sodium Lauryl 15.00 15.00 — Sulphate added asEmulsifier in above Water (g) 3 Wt. of Diesel added to 302.84 301.09300.21 above Water (g) 4 Wt. of Prepared Sludge (g) 619.95 617.93 600.325 Wt. % Water in above 48.38 48.31 49.13 Prepared Sludge as determinedby BTX 6 Calorific Value (kcal/kg) 5,550 5,518 5,503

TABLE 2.5 CENTRIFUGING DETAILS SI. No. DESCRIPTION Test 1 Test 2 Test 31 Time taken in mints to 2.92 2.50 2.50 Reach Max. Relative CentrifugalForce 2 Max. Relative Centrifugal 3,502 21,893 21,893 Force at theCentrifuge was operated 3 Holding Time at Max. 1.00 13.00 10.00 RelativeCentrifugal Force in mints 4 Time taken to come 2.37 3.50 3.50 back tozero Relative Centrifugal Force 5 Total Residence Time in 6.29 19.0016.00 mints inside centrifuge

TABLE 2.6 RESULTS OF PRE-TREATMENT OF DIESEL SLUDGE SAMPLES INCENTRIFUGE SI. No. DESCRIPTION Test 1 Test 2 Test 3 1 Wt. % Sludgerecovered 65.87 45.18 0.00 having Bound Water therein 2 Wt. % BoundWater in 33.65 6.44 — above Sludge as determined by BTX 3 CalorificValue of 7,185 10,160 — Sludge with Bound Water (kcal/kg) 4 Wt. % SlopOil that 28.01 49.79 46.12 Separated Out from above Prepared Sludge 5Oil Content in Slop 2,02,883 1,43,656 37 Oil (ppm) 6 Wt. % Oil lostthrough 1.36 0.81 2.87 adhering to Various Surfaces 7 Wt. % Water lost4.76 4.21 2.86 through Evaporation and Wetting of Surfaces

Incoming ONGC Lagoon Sludge:

TABLE 2.7 CENTRIFUGING DETAILS SI. No. DESCRIPTION TEST 1 TEST 2 TEST 31 Wt. of Sludge taken for 700.08 700.91 2,115.91 treatment (g) 2 Wt. %Water in above 40.28 39.97 40.95 Sludge as determined by BTX 3 Wt. % AshContent in 3.68 3.68 3.70 above Oil 4 Calorific Value of 6,018 6,0385,945 above Sludge (kcal/kg) 5 Time taken in mints 2.80 2.75 2.67 toReach Max. Relative Centrifugal Force 6 Max. Relative Centrifugal 4,5004,500 21,893 Force at the Centrifuge was operated 7 Holding Time at Max.0.00 10.00 10.00 Relative Centrifugal Force in mints 8 Time taken tocome back 16.50 16.65 2.17 to zero Relative Centrifugal Force 9 TotalResidence Time 19.3 29.45 14.83 in mints inside centrifuge

TABLE 2.8 RESULTS OF PRE-TREATMENT OF ONGC SLUDGE SAMPLES IN CENTRIFUGESI. No. DESCRIPTION TEST 1 TEST 2 TEST 3 1 Wt. % Sludge recovered havingBound 40.52 31.67 20.85 Water therein 2 Wt. % Bound Water in aboveSludge as 52.41 42.21 30.26 determined by BTX 3 Wt. % Ash Content inabove Sludge 7.61 8.61 7.23 4 Calorific Value of Sludge with Bound 4,2405,212 6,635 Water (kcal/kg) 5 Wt. % Oil that Separated Out from 40.3940.99 42.60 above Sludge 6 Wt. % Water in above Oil as determined 1.020.39 0.15 by BTX 7 Calorific Value of Oil (kcal/kg) 10,550 10,633 10,6818 Wt. % Ash Content in above Oil 1.06 0.88 0.73 9 Wt. % Slop Oil thatSeparated Out from 18.22 26.46 35.91 above Sludge 10 Oil Content in SlopOil (ppm) 0.00 0.00 0.00 11 Turbidity of Slop Oil (NTU) 122 398 1,132 12Wt. % Ash Content in above Slop Oil 0.61 2.04 5.18 13 Wt. % Oil + Ashlost through adhering 0.35 0.37 0.12 to Various Surfaces 14 Wt. % Waterlost through Evaporation 0.52 0.52 0.54 and Wetting of Surfaces

It was observed that there was no impact on furnace oil sludgescontaining up to 61 wt. % water while centrifuging the sludges withresidence time of 10 minutes at peak RCF value of 21,893, provided thatthe sludge was without emulsifier like SLS. The entire sludge wasretrieved back expect what might stick to the walls of centrifugebottles. This can be seen from Table 2.3, for the sludge with 50 wt. %water the calorific value was not rose. However, once wt. % water of thesludge exceeded certain threshold value, which lies between the valuesof 61 to 70, then even without SLS, if a Furnace Oil Sludge wascentrifuged for 10 minutes at a peak RCF of 21,893 it was found to bedivided into sludge with bound water and slop oil. It was observed thatif the sludge was having 70 wt. % water and nil SLS, then it was foundto be divided such that 53 wt. % of the sludge was containing 44 wt. %water and the entire water was bound water. The remaining material wasfound to be the slop oil. Alternatively, it was observed that if furnaceOil containing 96 wt. % water and nil SLS, then on centrifuging it for10 minutes at a peak RCF of 21,893 the sludge was found to be dividedsuch that only 6 wt. % of it forming the sludge with 40 wt. % water, theentire water being bound water, and the remaining material mostly asslop oil. It was further observed that beyond 70 wt. % water, withincreasing water content, there was less yield of sludge with boundwater in it. However, it was observed that the quantum of bound waterinside the sludge does not vary much. Moreover, it was observed that forthe less yield of sludge more slop oil was obtained.

Further, it was observed that for furnace oil sludge with 96 wt. % waterwas having a meagre calorific value of 320 kcal/kg. However, oncentrifuging the sludge for 10 minutes at a peak RCF of 21,893 ityielded 6 wt. % sludge and that the sludge was having 19 times moreenergy density in it at 6,130 kcal/kg. Here by centrifuging it separatedheavier lumps of Sludge, where energy was relatively concentrated fromthe slop oil that has very less energy in it.

Further, it was observed that centrifuging of the furnace oil sludge for10 minutes at RCF of 21,893 with emulsifier like SLS in the sludge farlesser quantity of sludge was generated with bound water as compared tosimilar sludge without SLS. However with SLS, the quality of sludge wasfar better as it had a lot higher calorific value, on account of farless water content. Here again a centrifuge created a value by squeezingout water from within the sludge. This was possible only because of thepresence of SLS, which partially reduced the ability of sludge to holdonto water on account of its viscosity. However, it was observed thatSLS helped to make a centrifuge effective and without SLS the centrifugewas having no impact on the sludge.

Also, it was observed that centrifuging with diesel sludge for 13minutes at RCF of 21,893 adds value only when the sludge was havingemulsifier like SLS in it. This was possible only when the water wasbound to the diesel. However, without SLS, water was found to beseparated from the diesel without any sludge formation. But once SLS ispresent, the centrifuging was able to concentrate 87 wt. % diesel intothe sludge with just 6.44 wt. % water thereby nearly doubling the energydensity within the sludge in no time up to a value of 10,160 kcal/kgwhich was found to be 92% of energy density of pure diesel.

Also, it was observed that with diesel sludge having SLS, the valueadded by centrifuging depends both on the residence time provided andthe peak RCF value chosen. Here cumulative impact of centrifuging wasfound to be a helping factor. It was observed that with centrifuging ofdiesel sludge having SLS for 1 minute at RCF of 3,502, the squeezing outof water was found to be less. Consequently the quantum of sludgegenerated was found to be increased from 45 wt. % to 66 wt. % while theincrease in energy density falls from 84% to 29%. This can be seen fromTable-2.6.

It was observed that, without SLS, there was no binding between dieseland water. The centrifuge was found to be quickly separating the twothereby giving pure diesel at one end. However, with SLS present, thediesel delivered was not entirely water free. Hence to that extent, fromthe perspective of a centrifuge, SLS was found to aid in cases offurnace oil based sludges and hinder in case of diesel based sludges.Accordingly, with diesel sludge it was established that a batch typecentrifuge can break emulsifier based bonds between water and diesel.Often centrifuges are not expected to remove bound water. However, thebond breaking was more pronounced with increased residence time at ahigher RCF value.

It was observed that the best impact of pre-treatment of sludge with acentrifuge was seen with ONGC lagoon sludge which can be seen fromTables 2.7 and 2.8. Here, it was observed that one can enhancecommercial value of sludge by extracting from it 41 wt. % of saleable,free flowing hydrocarbons with a calorific value of 10,633 kcal/kg, ashcontent of 0.88 wt. % and moisture content of 0.39 wt. %. Besides, itwas also observed that one was able to reduce by weight of sludgerequiring further treatment by little more than three times withcommensurate benefits. Also, it was observed that with more residencetime or higher RCF value one was able to squeeze out more water. It wasalso observed that pre-treatment of sludge helped in reducing salt andash contents in hydrocarbons. Further, it was confirmed that onlycentrifuge cannot remove entire water from the sludge. It was observedthat the centrifuge enhances acceleration due to gravity by enormouslyspeeding up the naturally occurring separation of two differentimmiscible liquids due to their density difference. It was observed thatthe centrifuge was helping when mean free path between tiny droplets ofa particular liquid is small followed by consolidating them into muchlarger droplets with reduced drag, which then helped them move evenfaster.

Further it was observed that varying acceleration between movingdroplets leads to a lot larger number of collisions in a given time andhence faster consolidation followed by setting up a chain effect. Also,with enhanced residence time, droplets of two different liquids keepgathering kinetic energy while moving in opposite directions. Once thekinetic energy difference between them exceed a threshold value, thenthey were able to break the forces that might be binding these dropletstogether thereby affecting a permanent separation between them, whichotherwise would have been difficult to achieve with on-line centrifugescapable of operating at similar RCF. Accordingly, separation betweenconstituents on lagoon sludge from ONGC was ascertained. Further, it,was observed that free water can be collected from ONGC Sludge, behindthe impervious, viscous layer of hydrocarbons with bound water, inspiteof the fact that lumps of viscous layer emerge before the free wateremerges while centrifuging. Lastly, it was observed that constituents oflagoon sludge do not naturally separate out with time, even afterdecades wherein quantum of bonds broken depend on both the operative RCFof centrifuge and the residence time of sludge within the centrifuge.

Example-3 Effect of Using Xylene as Solvent on Sludges with Bound Water

An impact on release of bound water from sludges with time was studiedby reducing their viscosities through addition of varying amounts of lowviscous solvents like Xylene, at ambient and elevated temperatures.Also, it was discovered how water could be held tightly by hydrocarbons.Accordingly, about 58 wt. % and 200 wt. % xylene was added to viscousFurnace Oil Sludges without SLS prepared in-house with 50 wt. % boundwater therein. Alternatively, about 58 wt. % and 200 wt. % xylene wasadded to viscous furnace oil sludge with 20.47 wt. % bound water and3.74 wt. % SLS, extracted from in-house Sludge with 47.5 wt. % water and2.51 wt. % SLS, by centrifuging that for 10 minutes at 21,893 RCF.Further, about 58 wt. % and 200 wt. % xylene was added to viscous ONGCsludge with 42.21 wt. % bound water and 8.61 wt. % ash that wasrecovered from batch centrifuging of in-coming ONGC Lagoon Sludge for 10minutes at 4,500 RCF. Subsequently, the mixture was stirred well andkept a part of that low viscous mixtures in the settling vessels for 6and 72 hours at a stretch at ambient temperature of about 28 to 32° C.while keeping a yet another set of samples for 6 hours in a water bathat 80-85° C. At the end of test period, fractions of material from top,middle and bottom of the settling vessels were removed and evaluated forwater content using the BTX process. Subsequently, water present invarious levels with the average water content of the entire mixture wasmeasure. While top-most layer was often nearly water free, no free wateror slop oil was found to be collected at the bottom-most layer. Thebottom-most layer was composition wise similar to the middle layer andhence added the same in Table Nos. 3-2, 3-4, 3-6 and 3-9.

Furnace Oil Based Sludges with 50 wt. % Water—

TABLE 3.1 CONSTITUENTS IN FURNACE OIL SLUDGE PLUS XYLENE MIXTURES SI.Sample Sample Sample No. DESCRIPTION # 1 # 2 # 3 1 Wt. of Sludge withBound 2,319.30 808.29 587.45 Water (g) 2 Wt. % Bound Water in 50.0049.75 20.47 above Sludge as per BTX 3 Wt. % Sodium Lauryl 0.00 0.00 3.74Sulphate in Sludge 4 Wt. of Xylene Added & 1,389.40 1604.17 1162.73mixed with above Sludge (g) 5 Wt. % Xylene in total 37.46 66.50 66.43mixture 6 Wt. % Water in above 31.27 16.67 6.87 Sludge with Xylene 7Total amount of Sludge + 3,708,70 2412.46 1,750.18 Xylene Mixtureprepared for Treatment (g)

TABLE 3.2 TEST RESULTS WITH 37 WT. % XYLENE IN FURNACE OIL SLUDGEWITHOUT EMULSIFIER Kept in Kept at Kept at Water Bath at SI. 30° C. for30° C. for (80-85° C.) for No. DESCRIPTION 6 Hours 72 Hours 6 Hours 1Wt. of above Sludge + 1,005.46 1,002.91 1,002.70 Xylene Mixture takenfor specific Treatment (g) 2 Wt. of Water-Free 65.50 66.46 61.34 Layerwith Solvent + Furnace Oil Collected (g) 3 Wt. of Layer with 917.68898.02 889.61 Solvent + Furnace Oil With Bound Water Collected (g) 4 Wt.of Slop Oil 0.00 0.00 0.00 Collected (g) 5 Wt. of Material Sticking21.60 32.30 27.83 to the Surfaces (g) 6 Wt. % Evaporation Loss 0.0680.611 2.386

TABLE 3.3 STUDY OF WT. % WATER AT DIFFERENT LAYERS WITHIN MATERIAL WITH37 WT. % XYLENE IN FURNACE OIL SLUDGE WITHOUT EMULSIFIER Kept in Kept atKept at Water Bath at SI. 30° C. for 30° C. for (80-85° C.) for No.DESCRIPTION 6 Hours 72 Hours 6 Hours 1 Wt. % Water in top 5.5 27.77 0.170.07 Vol. % of this layer as determined by BTX 2 Corrected Wt. % Water28.51 8.59 28.11 in Top 5.5 Vol. % after adding back the amountevaporated 3 Wt. % Water in Middle 31.65 33.00 32.66 89 Vol. % of thislayer as determined by BTX 4 Wt. % Water in Bottom 31.75 38.75 41.68 5.5Vol. % of this layer as determined by BTX

TABLE 3.4 EFFECT OF 66.5 WT. % XYLENE IN FURNACE OIL SLUDGE WITHOUTEMULSIFIER Kept in Kept at Kept at Water Bath at SI. 30° C. for 30° C.for (80-85° C.) for No. DESCRIPTION 6 Hours 72 Hours 6 Hours 1 Wt. ofabove Sludge + 493.78 655.1 329.44 Xylene Mixture taken for specificTreatment (g) 2 Wt. of Water-Free Layer 38.71 46.32 26.54 with Solvent +Furnace Oil Collected (g) 3 Wt. of Layer with 446.98 583.57 266.16Solvent + Furnace Oil With Bound Water Collected (g) 4 Wt. of Slop Oil0.00 0.00 0.00 Collected (g) 5 Wt. of material sticking 7.85 20.05 21.50to surfaces (g) 6 Wt. % Evaporation Loss 0.049 0.788 4.626

TABLE 3.5 STUDY OF WT. % WATER AT DIFFERENT LAYERS WITHIN MATERIAL WITH66.5 WT. % XYLENE IN FURNACE OIL SLUDGE WITHOUT EMULSIFIER Kept in Keptat Kept at Water Bath at SI. 30° C. for 30° C. for (80-85° C.) for No.DESCRIPTION 6 Hours 72 Hours 6 Hours 1 Wt. % of total treated 7.97 7.359.07 material, in the top most layer 2 Wt. % Water in the 0.31 0.56 4.79top-most layer as determined by BTX 3 Corrected Wt. % Water 0.92 10.5339.52 in Top most layer after adding back the amount evaporated 4 Wt. %of total treated 80.69 79.20 79.89 material, in the middle layer 5 Wt. %Water in Middle 15.03 8.82 5.67 Layer as determined by BTX 6 Wt. % oftotal treated 11.34 13.45 11.05 material, in the bottom most layer 7 Wt.% Water in Bottom 40.24 69.10 80.14 most layer as determined by BTX

TABLE 3.6 EFFECT OF Wt. 66.5 WT. % XYLENE IN FURNACE OIL SLUDGE WITHEMULSIFIER Kept in Kept at Kept at Water Bath at SI. 30° C. for 30° C.for (80-85° C.) for No. DESCRIPTION 6 Hours 72 Hours 6 Hours 1 Wt. ofabove Sludge + 328.09 325.53 321.66 Xylene Mixture taken for specificTreatment (g) 2 Wt. of Water-Free Layer 28.40 17.63 27.91 with Solvent +Furnace Oil Collected (g) 3 Wt. of Layer with 291.71 290.59 279.95Solvent + Furnace Oil With Bound Water Collected (g) 4 Wt. of Slop Oil0.00 0.00 0.00 Collected (g) 5 Wt. of material sticking 7.76 15.11 11.75to surfaces (g) 6 Wt. % Evaporation Loss 0.07 0.68 0.64

TABLE 3.7 STUDY OF WT. % WATER AT DIFFERENT LAYERS WITHIN MATERIAL WITH66.5 WT. % XYLENE IN FURNACE OIL SLUDGE WITH EMULSIFIER Kept in Kept atKept at Water Bath at SI. 30° C. for 30° C. for (80-85° C.) for No.DESCRIPTION 6 Hours 72 Hours 6 Hours 1 Wt. % of total treated 8.87 5.729.07 material, in the top most layer 2 Wt. % Water in the 0.21 0.17 0.18top-most layer as determined by BTX 3 Corrected Wt. % Water 1.01 11.297.04 in Top most layer after adding back the amount evaporated 4 Wt. %of total treated 77.52 79.35 78.38 material, in the middle layer 5 Wt. %Water in Middle 6.78 4.80 4.82 Layer as determined by BTX 6 Wt. % oftotal treated 13.60 14.93 12.55 material, in the bottom most layer 7 Wt.% Water in Bottom 12.22 18.14 21.56 most layer as determined by BTX

TABLE 3.8 CONSTITUENTS IN ONGC SLUDGE PLUS XYLENE MIXTURES SI. SampleNo. DESCRIPTION # 1 1 Wt. of Sludge with Bound Water (g) 438.66 2 Wt. %Bound Water in above Sludge as per BTX 42.21 3 Wt. % Ash in Sludge 8.614 Wt. of Xylene Added & mixed with above Sludge (g) 882.71 5 Wt. %Xylene in final mixture 66.80 6 Wt. % Water in above Sludge with Xylene14.01 7 Total amount of Sludge + Xylene Mixture 1,321.37 prepared forTreatment (g)

TABLE 3.9 EFFECT OF 66.5 WT. % XYLENE IN ONGC SLUDGE Kept in Kept atKept at Water Bath at SI. 30° C. for 30° C. for (80-85° C.) for No.DESCRIPTION 6 Hours 72 Hours 6 Hours 1 Wt. of above Sludge + 333.65333.96 332.14 Xylene Mixture taken for specific Treatment (g) 2 Wt. ofWater-Free Layer 28.92 19.93 24.68 with Solvent + Furnace Oil Collected(g) 3 Wt. of Layer with 295.97 303.91 248.08 Solvent + Furnace Oil WithBound Water Collected (g) 4 Wt. of Slop Oil Collected 0.00 0.00 0.00 (g)5 Wt. of material sticking 8.55 6.56 46.09 to surfaces (g) 6 Wt. %Evaporation Loss 0.06 1.07 4.00

TABLE 3.10 STUDY OF WT. % WATER AT DIFFERENT LAYERS WITHIN MATERIAL WITH66.5 WT. % XYLENE IN ONGC SLUDGE Kept in Kept at Kept at Water Bath atSI. 30° C. for 30° C. for (80-85° C.) for No. DESCRIPTION 6 Hours 72Hours 6 Hours 1 Wt. % of total treated 8.90 6.15 9.05 material, in thetop most layer 2 Wt. % Water in the 11.76 2.31 2.71 top-most layer asdetermined by BTX 3 Corrected Wt. % Water 12.36 17.15 36.75 in Top mostlayer after adding back the amount evaporated 4 Wt. % of total treated79.59 79.51 78.75 material, in the middle layer 5 Wt. % Water in Middle14.08 13.58 7.92 Layer as determined by BTX 6 Wt. % of total treated11.51 14.33 12.20 material, in the bottom most layer 7 Wt. % Water inBottom 16.37 16.01 43.81 most layer as determined by BTX

In earlier Example-1, it was observed that on addition of externalemulsifiers like Sodium Lauryl Sulphate to furnace oil based sludgescontaining up to 61 wt. % water with respect to the total water therein,the amount of water held by Furnace Oil as bound water, dropped downfrom 100% to a much lower level. For sludges with 48-49 wt. % water init, when SLS added was 2.4 to 2.5 wt. %, we found only 25-23 wt. % oftotal water present in Sludge, remained stuck to furnace oil as boundwater. But that was measured only after subsequently centrifuging thesludge for 10 minutes at 21,893 RCF. However, in accordance with thepresent Example-3, the furnace oil sludge with 47.52 wt. % water and2.51 wt. % SLS in it, centrifuging for 10 minutes at 21,893 RCF aviscous sludge was retrieved containing 20.47 wt. % bound water and 3.74wt. % SLS therein. The obtained viscous sludge with 20.47 wt. % boundwater alone was taken for the treatment.

In earlier Example-2, it was observed that on batch centrifuging ofincoming ONGC Lagoon Sludge for 10 minutes at 21,893 RCF or even at4,500 RCF, the sludge got separated into 3 different layers and middlelayer was a viscous sludge with 30 wt. % bound water therein. When RCFwas just 4,500, the middle layer had 42.21 wt. % total water in it, ofwhich only 72 wt. % was bound water. However, in accordance with presentExample-3, it was evaluated that the middle layer after centrifugingin-coming ONGC sludge for 10 minutes at 4,500 RCF produced 42.21 wt. %total water in it. In other words, addition of xylene as solvent toviscous sludges alone, where except for ONGC Sludge the entire water wasbound so tightly to hydrocarbons that even on centrifuging for 10minutes at 21,893 RCF there was no separation of water. Also it wasobserved that with ONGC Sludge, at this high RCF only 28 wt. % of waterwas separated.

Accordingly, it was observed that Xylene dramatically reduced viscosityof the resultant mixture especially when the quantity thereof was addedtwice that of the sludge. Further, the resultant mixture was heated at80° C.-85° C. to further reduce the viscosity thereof. Apart fromreducing viscosity immediately, Xylene was believed to enhance thedensity difference between immiscible hydrocarbons and water. However,it was observed that no free water or slop oil could separate out evenafter waiting for 6 hours. Hence, it was confirmed that viscosity alonewas not responsible for hydrocarbons to hold onto such large amounts ofwater.

As shown in Table 3.1, it was observed that the mixture held even up to3.1.27 wt. % water on an average. It was observed that the dispersedwater droplet size was so tiny that even with viscosity got immediatelyreduced and density difference slowly got enhanced. However the dragexperienced by them remained too high to allow their rapid separation.In addition, it might be probably because of dispersed water dropletsize being just so small that inspite of 10 minutes of stay within acentrifuge operating at such large RCF, still immiscible water could notseparate from hydrocarbons even when it was present in quantity as highas 50 wt. %.

In order to evaluate the extent of impact of addition of Xylene to thesludge on downward percolation of bound water with time, the table Nos.3.3, 3.5, 3.7 and 3.10 were read horizontally for the Top-Most, Middle &Bottom-Most layers. Accordingly, it was observed that addition of xylenebeyond a certain threshold value is essential to get a large impact onfurnace oil based sludges. It was observed that for varied the quantumof Xylene added for Furnace Oil based sludges, Xylene was effective onlywhen it was present in the final mixture in the levels of 66 wt. % andthe benefit of Xylene was muted when presence thereof was limited to 37wt. %. It was observed that even the top-most layer was not anywherenear being water free with 37 wt. % Xylene present in the mixture.

Further, it was observed that there was no collection of free water orslop oil at the bottom but there was collection of nearly water freehydrocarbons at the top-most layer. In addition to the fact that a lotmore water got collected in the bottom most layer indicated that waterdroplets were actually very slowly moving down with time. Very slow rateof downwards percolation of water could either be because of presence ofemulsifiers or due to ultra small size of dispersed water droplets.Accordingly, it was identified that the density differential betweenwater and hydrocarbons diminished and that in turn reduced the force ofbuoyancy in case for water bound to oil due to emulsifiers. Accordingly,it was confirmed that in case of emulsifier being present theconcentration of water in the bottom most layer cannot exceed theaverage concentration of water present as much as what would be possiblein case there was no emulsifier where other things remaining the same.

Further, it was observed that using Xylene with additional heating onemay get water free top-most layer in about 6 hours, even from sludgeswith high water content, if condensed water vapours are prevented fromtrickling back into that layer or if one prevents the condensation ofregressing water vapors itself. But the time required for this will bemuch longer if emulsifiers are present in sludge. Also only a smallfraction of water free hydrocarbons can thus be released from sludges.

Further, it was observed that the temperature had two impacts on themixture. Firstly, apart from further reducing its viscosity, it enhancedthe rate of evaporation of water from the top-most layer. Again, thelatter had two implications. Firstly, it helped to reduce water in thetop-most layer. Secondly, it enhanced the rate of condensation. Part ofour settling vessel projected out above the water level in water bath.Hence, its top portion was relatively cooler, allowing rapidcondensation. With that, droplets of condensed water rapidly trickledback into the top-most layer. That in turn explained why we had morewater in the top-most layer as observed from Tables 3.5, 3.7 and 3.10.

Also, it was observed that egressing water vapors could be prevented bynot allowing the top end of our settling vessel kept in water bath tocool down in addition to getting much drier top-most layer. That couldalso be achieved by preventing the condensed water from trickling backinto the top-most layer by modifying the design of our settling vesselitself.

It was observed that with reduced Xylene and relatively higher viscosityin the mixture as seen in Table Nos. 3.5, 3.7 and 3.10 and not repeatedin Table 3.3. It was observed that it might have an adverse impact onthe rate of evaporation. It was seen that when xylene present in themixture was limited to 37 wt. % then only 2.39 wt. % of the mixtureevaporated by way of water vapour. However, when xylene present inmixture rose to 66.5 wt. % then about 4.63 wt. % of the mixtureevaporated by way of water vapour. Accordingly, it was confirmed thatwith less evaporation there was less condensation and hence less harmwas done through condensation. This can be ascertained by comparingTable Nos. 3.2 and 3.4. Besides, in Table 3.3, the top-most layerconsisted of just 6.12 wt. % of total mixture as against 9.07 wt. % inTable 3.5 where more xylene was used. By considering a thinner layerthere was lesser moisture in top-most layer in as can be seen in Table3.3.

However, in presence of SLS very low evaporation rate was observedinspite of equally large reduction is viscosity. It was because whenwater was bound to hydrocarbons through emulsifier, the boiling pointthereof under a given pressure went high and with that evaporation rateat a given temperature came down along with condensation rate.

Accordingly it was observed that when water is bound to hydrocarbonsthrough emulsifier, entire water or hydrocarbons may or may not bebound. Hence the process of separation between them becomes slow andincomplete without being completely ceased. Hence when emulsifier ispresent, deviation from average water content in any layer was observedto be less than that without emulsifier. This too was borne out fromTable Nos. 3.5 and 3.7.

An important observation with ONGC Sludge was that even after reducingits viscosity immensely by adding twice as much its own weight of xylenethere was little impact on downwards percolation of bound water presenttherein under ambient conditions. As can be seen from Table 3.10, theaverage water content in bottom most layer even after waiting for 72hours rose to 16 wt. % when overall water content of mixture itself was14 wt. %. In contrast, for Furnace Oil Sludge when twice its weight ofXylene was added the average water content became 16.67 wt. %. But after72 hours of waiting, water in bottommost layer rose to 69 wt. %, whichis nearly 4 times as much. With ONGC Sludge additional heat however hadan immense impact though not as much as that seen with Furnace OilSludge.

It was further observed that solvent, even when added in large amounts,it does not quickly and selectively solubilize entire hydrocarbonspresent in sludge and then disgorge out immiscible water due to densitydifference as commonly assumed. However, it was only found to weaken theforces that bind water and hydrocarbons together and to an extentadditionally helped by slowly enhancing density difference between themby slowly dissolving hydrocarbons in very small quantities at a time. Itcertainly did not entirely or immediately eliminate the forces that bindwater with hydrocarbons.

Example-4 Combined Effect of Centrifuge & Solvent on Sludges with BoundWater

In order to understand the mechanism and also the impact on the releaseof bound water from hydrocarbons firstly by reducing viscosity ofvarious sludges followed by adding solvents, such that the mixturecontains 67 wt. % solvents, subsequently centrifuging it for 10 minutesat 4,500 RCF and at ambient temperature of about 28 to 32° C. wasstudied. Specifically, solvents like Xylene and Toluene were added toviscous furnace oil sludge prepared in-house with 50 wt. % water.Alternatively, solvents like Xylene and Toluene were added to viscousfurnace oil sludge with 20.47 wt. % bound water and 3.74 wt. % SLS,extracted from in-house Sludge with 47.5 wt. % water and 2.51 wt. % SLS,by centrifuging that for 10 minutes at 21,893 RCF. Alternatively,solvents like Xylene and Toluene were added to viscous ONGC sludge with42.21 wt. % bound water recovered after batch centrifuging in-comingONGC Lagoon Sludge for 10 minutes at 4,500 RCF such that the mixturecontains 67 wt. % solvent and then after stirring immediately subject itto non-stop centrifuging at 4,500 RCF for 10 minutes. The process ofcentrifuging produced two or three distinct layers of liquids. The thirdlayer was obtained only in case of ONGC Sludge containing clear water.The Top-most layer was invariably water free. It was containing bulk ofsolvent added and also large amounts of hydrocarbons released fromsludge. The middle layer, in cases where three layers were obtained, wasconsisting of hydrocarbons and water. Subsequently, the middle layer wasevaluated. On centrifuging it for 10 minutes at 21,893 RCF we got sludgewith bound Water, albeit much smaller in quantity, a free flowing layerof solvent plus some dissolved hydrocarbons and slightly coloured slopoil. The sludge thus obtained was then evaluated for bound water usingBTX and calorific value using Bomb calorimeter.

Furnace Oil Based Sludges with Bound Water—

TABLE 4.1 DESCRIPTION OF FURNACE OIL SLUDGE SI. Sample Sample Sample No.DESCRIPTION # 1 # 2 # 3 1 Wt. of Sludge taken 469.69 234.47 233.55 forTreatment (g) 2 Wt. % Sodium Lauryl 3.74 — — Sulphate 3 Wt. % Water inabove 20.47 49.91 49.91 Sludge as determined by BTX 4 Calorific Value ofabove 7,970 5,110 5,110 Sludge (kcal/kg) 5 Name of Solvent Used XyleneToluene Xylene 6 Wt. of Solvent Added 940.87 469.75 467.18 (g) 7 FinalWt. of Sludge 1,410.56 704.22 700.73 with Solvent (g)

TABLE 4.2 CENTRIFUGING DETAILS SI. Sample Sample Sample No. DESCRIPTION# 1 # 2 # 3 1 Time taken in minutes 2.65 2.70 2.65 to Reach Max.Relative Centrifugal Force 2 Max. Relative Centrifugal 4,500 4,500 4,500Force on which operated 3 Holding Time at Max. 10 10 10 RelativeCentrifugal Force in mutes 4 Time taken to come 17 16.5 16.5 back tozero Relative Centrifugal Force 5 Total Residence Time 29.65 29.20 29.15in minutes inside centrifuge

TABLE 4.3 COMBINED EFFECT OF CENTRIFUGE WITH SOLVENT ON FURNACE OILSLUDGE SI. Sample Sample Sample No. DESCRIPTION # 1 # 2 # 3 1 Wt. ofFurnace Oil Sludge + 1,408.38 702.94 699.59 Solvent Mixture taken forCentrifuge (g) 2 Wt. of top Most Layer with 703.66 566.16 553.03 FurnaceOil + Solvent Recovered (g) 3 Wt. % of Top Most Layer 49.96 80.54 79.054 Wt. of Solvent in Top Most 696.62 466.32 453.54 Layer (g) 5 Wt. ofFurnace Oil with 6.83 99.42 99.50 0.23 wt. % ash in Top Most Layer (g) 6Wt. % Water in Top Most 0.03 0.06 0.00 Layer as determined by BTX 7Calorific Value of Material in Top Most Layer in kcal/kg 8 Wt. of MiddleLayer 699.00 134.60 144.68 containing Furnace Oil + Water + Solvent +Ash + Emulsifier if any, inclusive of material sticking on surfaces orevaporated (g) 9 Wt. % of Middle Layer 49.63 19.15 20.68 10 Wt. ofSludge with Bound 663.80 94.46 104.81 Water + Solvent + Emulsifier + Ashin Middle Layer in (g) 11 Wt. of Solvent + Free 0.00 1.25 12.92 FlowingFurnace Oil + Ash + Emulsifier in Middle Layer (g) 12 Wt. of slightlycoloured 35.20 38.89 26.95 Free Water in Middle Layer with Emulsifier &Ash (g) 13 Wt. % of Sludge with Bound 94.96 70.18 72.44 Water, Ash andEmulsifier found within the Middle Layer 14 Wt. % Water in above Sludge9.07 81.66 85.02 from within the Middle Layer as determined by BTX 15Calorific Value of above 9,124 1,860 1,518 Sludge in kcal/kg 16 Wt. ofClear Water with Ash 0.00 0.00 0.00 & Emulsifier in Bottom Most layer(g) 17 Wt. % of Bottom Most Layer 0.00 0.00 0.00 18 Wt. of loss ofmaterial in (g) 5.72 2.18 1.88 19 W % of Loss of Material 0.41 0.31 0.27ONGC Viscous Sludge with Bound Water—

TABLE 4.4 DESCRIPTION OF ONGC VISCOUS SLUDGE SI. Sample Sample No.DESCRIPTION # 1 # 2 1 Wt. of Sludge taken for 212.86 233.53 Treatment(g) 2 Wt. % Water in above Sludge 42.21 42.21 as determined by BTX 3Calorific Value of above 5,213 5,213 Sludge (kcal/kg) 4 Name of SolventUsed Toluene Xylene 5 Wt. of Solvent Added (g) 492.33 468.74 6 Final Wt.of Sludge with 705.19 702.27 Solvent (g)

TABLE 4.5 CENTRIFUGING DETAILS SI. Sample Sample No. DESCRIPTION # 1 # 21 Time taken in minutes to Reach Max. 2.68 2.56 Relative CentrifugalForce 2 Max. Operative Relative Centrifugal 4,500 4,500 Force 3 HoldingTime at Max. Relative 10.00 10.00 Centrifugal Force in minutes 4 Timetaken to come back to zero Relative 16.60 16.50 Centrifugal Force inminutes 5 Total Residence Time in minutes inside 29.28 29.06 thecentrifuge

TABLE 4.6 COMBINED EFFECT OF CENTRIFUGE WITH SOLVENT ON ONGC SLUDGE SI.Sample Sample No. DESCRIPTION # 1 # 2 1 Wt. of Mixture taken forCentrifuge (g) 705.08 702.14 2 Wt. of top Most Layer with Furnace 534.30511.47 Oil + Solvent Recovered (g) 3 Wt. % of Top Most Layer 75.78 72.844 Wt. of Solvent in Top Most Layer (g) 481.92 455.88 5 Wt. of ONGCHydrocarbons in Top Most 44.17 47.52 Layer (g) 6 Wt. of Ash in Top MostLayer (g) 8.10 7.98 7 Wt. % Water in Top Most Layer as 0.02 0.02determined by BTX 8 Calorific Value of Top Most Layer (kcal/kg) 9 Wt. ofMiddle Layer containing ONGC 108.29 131.13 Hydrocarbons + Water +Solvent + Ash, inclusive of material sticking on surfaces or evaporated(g) 10 Wt. % of Middle Layer 15.36 18.68 11 Wt. of Sludge with boundwater in 73.58 92.90 Middle Layer in (g) 12 Wt. of Solvent and freeFlowing 14.51 16.18 Hydrocarbons with ash in Middle Layer (g) 13 Wt. ofUnbound, slightly coloured Water 20.20 22.05 with ash in Middle Layer(g) 14 Wt. % Sludge in Middle Layer 67.95 70.85 15 Wt. % Bound Water inabove Sludge in 12.52 22.02 Middle Layer as determined by BTX 16Calorific Value of Sludge in Middle 8,098 7,149 Layer in kcal/kg 17 Wt.of Bottom Most Layer containing 60.00 56.91 clear water (g) 18 Wt. % ofBottom Most Layer 8.51 8.11 19 Turbidity of Bottom Most Layer (NTU) 20.219.08 20 Wt. of un-accountable loss of Material 2.48 2.63 (g) 21 Wt. %Loss of Material 0.35 0.37

It was observed that combining solvent with centrifuge does a lot morethan mere addition of their individual effects. For example, Furnace OilSludge without external emulsifier and with 50 wt. % water could notremove any water or oil after centrifuging it for 10 minutes at 21,893RCF. Subsequently, by adding similar quantum of same solvent we couldget only 8 wt. % of the mixture, in the top most layer with 0.31 wt. %water, after waiting for 6 hours. However, even at reduced peak RCF ofcentrifuge to 4,500, i.e. by 4.9 times, thereby keeping the residencetime at peak RCF the same it was possible to collect 80 wt. % of themixture in top-most layer with nil water in it, in just time of 30minutes. This was mostly because by combining the solvent and centrifugeenhanced the factors that contribute to increase force of buoyancy thatnaturally helps separating two immiscible liquids. However, on otherhand combining the solvent and centrifuge by reducing viscosity drag wassubstantially reduced that inhibited such separation.

As can be clearly seen from Table Nos. 4.1 to 4.3, in case of furnaceoil sludge with emulsifier like SLS, the size of topmost water-freelayer shrinks sharply from 80 to 50 wt. %. This clearly established thateven a combination of solvent and centrifuge is less effective whenwater is additionally bound to hydrocarbons through an emulsifier. Withshrinking of the top most layer, middle layer expanded from 20 wt. % to50 wt. % and while doing so the presence of sludge with bound watertherein went up from 72 to 95 wt. %. Even more important act was thatbound water in within higher fraction of sludge fallen from 85 wt. % to9 wt. % thereby enhancing the calorific value of that sludge from 1,520to 9124 kcal/kg.

With the presence of the emulsifier like SLS, the hydrocarbon componentin Sludge went up slightly from 76 to 87 wt. % while its water contentcame down from 20 to 9 wt. % on account of the combined treatment withSolvent and Centrifuge. But when SLS was not present, with sametreatment furnace oil component in the sludge fell down dramaticallyfrom 50 to 15 wt. % while water content therein went up from 50 to 85wt. %. When SLS was present, the mass of sludge required furthertreatment actually increased by 41 wt. % as compared to reduction by 55to 57 wt. % in the absence of SLS. This basically implied that withpresence of SLS, the increase in hydrocarbon content in sludge was notso much on account of some water moving out from it, but because of alot more solvent coming into it with very little amounts of furnace oilleaving the sludge. When SLS was present only 2 wt. % of furnace oilpresent in sludge left and moved into top most layer while 25 wt. % ofxylene added moved into the sludge and then got very tightly bounded towater. Here the topmost layer was consisting mostly of Xylene alone andhence it was only slightly coloured. On the contrary, in the absence ofSLS, about 86 wt. % of furnace oil present in sludge moved out into thewater-free topmost layer while nil xylene moved in. Hence it was only inthe absence of SLS that combination of xylene and centrifuge was able toremove 87 wt. % of furnace oil from within the sludge. Accordingly, thecombined effect of solvent with centrifuge was ascertained.

It was observed that with furnace oil sludge, use of Toluene as Solventwas found to be equally good as that of Xylene except for the fact thatwith Toluene the mass of sludge was found to be shrinked by about 4.6wt. % more time and reduced its water content by about 3.3 wt. % more ascompared to xylene thereby raising its calorific value from 1,520 to1,860 kcal/kg. Also with Toluene the middle layer was found to containless amount of solvent with dissolved hydrocarbon therein.

Toluene was observed to remove 85 wt % hydrocarbons present in sludgealong with 34 wt. % of water as against Xylene removing 86 wt. %hydrocarbons along with 87 wt. % hydrocarbons and 26 wt. % water presentin sludge. Toluene was found to extract water from the sludge in arelatively better manner while Xylene seems to extract hydrocarbons alittle better manner in comparison to Toluene.

It was observed with ONGC sludge that the combined use of solvent andcentrifuge can remove free water with turbidity values in the range of20 NTU. In case of ONGC Sludge, Toluene was preferred over Xylene as itreduced mass of sludge with bound water by a factor of 2.89 against withthat of 2.51 with Xylene. Similarly, the factors for furnace oil sludgewithout external emulsifier were respectively observed to be 2.48 and2.30. Hence the combination of solvent cum centrifuge was found to workbetter with ONGC sludge. In case of ONGC sludge, Toluene was found toreduce hydrocarbon content in sludge by 48 wt. % while Xylene reduces itby 46 wt. %. Similar figures for furnace oil sludge without externalemulsifier are 85 wt. % and 87 wt. % respectively.

In case of ONGC Sludge, Toluene was found to reduce water content insludge by 90 wt. % while Xylene was found to reduce the water content by79 wt. %. Similarly, for furnace oil based sludge without externalemulsifier, Toluene was found to reduce water content in sludge by 34%and Xylene was found to reduce water content in the sludge by 26 wt. %.

Hence, it was confirmed that water content is far more easilyextractable in case of ONGC sludge as compared to furnace oil basedsludge without external emulsifier. This was also seen by free watercollecting at the bottom. Toluene was found to be particularly farbetter when removal of water from the sludge. Accordingly, use ofToluene was preferred for ONGC sludge.

Further, it was observed that removal of bound water from the sludgepreferred rather than extraction of hydrocarbons from sludge becauseremoval of bound water from the sludge was found to increase calorificvalue of sludge without loading too much of hydrocarbons in solvent.However, the solvent can be reused as such prior to separatinghydrocarbons from solvent when solvent has fewer hydrocarbons therein.

In case of ONGC Sludge, it was possible to extract close to 50 wt. %hydrocarbons from the sludge containing bound water therein withoutloading solvent with hydrocarbons in topmost layer beyond 8.5 or 9.5 wt.% when using Toluene and Xylene respectively. This was because a lot ofreleased hydrocarbons were not solubilised by solvent collected intopmost water-free layer.

Example-5 Study of Pure Azeotropic Boiling with Water

A study was conducted in order to understand and evaluate pureazeotropic boiling of solvents like Benzene, Toluene and Xylene withwater at an atmospheric pressure 933 mbar followed by comparison ofresults with similar values from the literature. A predefine weighedamounts of solvents and de-ionized water in certain proportions weretaken in Round Bottom (RB) Flask of Dean and Stark Apparatus followed byheating in a mantle furnace. A condenser having chilled water at 6° C.is attached to the RB flask where vapours of solvent and water arecondensed. A stop cork at bottom the receiver was positioned which wasperiodically opened to periodically collect the condensate and weigh theimmiscible constituents individually after separating them in theseparating flask. The temperature of material at near bottom in the RBFlask was continuously recorded using a digital thermometer.

TABLE 5.1 DESCRIPTION OF SOL VENTS USED SI. No. DESCRIPTION BenzeneToluene Xylene 1 Wt. % Water in Solvent through BTX 0.001994 0.0039960.003998 2 Calorific Value of Solvent (kcal/kg) 9,995 10,074 10,205 3Boiling Point of pure Solvent in ° C. 80.20 110.80 138.40 at Sea Levelas per Literature 4 Minimum Azeotropic Boiling Point in ° C. 69.30 84.1090.00 at Sea Level with Water as per Literature 5 Minimum AzeotropicBoiling Wt. Ratio with 10.24 3.95 1.50 Water per unit Wt. of Water asper Literature

TABLE 5.2 STUDY OF AZEOTROPIC BOILING OF SOLVENTS WITH WATER AT 933 mbarSI. No. DESCRIPTION Benzene Toluene Xylene 1 Wt. of Water Taken in RB100.35 150.40 306.94 Flask (g) 2 Wt. of Solvent Taken in RB 1003.42601.33 538.17 Flask (g) 3 Initial Wt. Ratio of Solvent 10.00 4.00 1.75to Water 4 Observed temperature range of 74.67- 93.4- 95.55- AzeotropicBoiling (° C.) 76.03 93.9 95.85 5 Initial Wt. Ratio of Solvent to 33.455.65 2.20 Water Collected 6 Final Wt. Ratio of Solvent to 102.15 10.142.23 Water Collected 7 Average Wt. Ratio of Solvent to 61.97 9.34 2.08Water Collected 8 Wt. Ratio of Solvent to Water 6.48 2.56 1.52 Left overin RB Flask at the End of Experiment 9 Wt. of Water left in RB Flask93.99 116.41 180.06 at the end of Experiment (g) 10 Wt. % Loss due toEvaporation, 0.38 0.67 0.36 etc.

It was observed that minimum azeotropic boiling point with water oughtto be a fixed point. Yet a small range for boiling point was observed.It was observed that inspite of lower atmospheric pressure at our place,on an average we get 6.05° C. higher minimum azeotropic boiling pointwith Benzene; 9.55° C. with Toluene and 5.7° C. with Xylene than whatwas reported in the literature. Part of this could be because there wasno stirrer inside the RB Flask.

In case of minimum azeotropic boiling weight ratio, higher values wereobserved than what was reported in the literature. It was observed thatfor Benzene, it was found to be higher by 3.3 times. For toluene,initially it was higher by 1.43 times. For Xylene, initially it washigher by 1.46 times. In case of benzene, quantity of solvent floatingover water was very high and therefore entrainment was also expected tobe the maximum.

It was observed that weight ratio of solvent emerging with water vaporincreased with time. This happened significantly only for Benzene andToluene. Moreover, the weight ratio of solvent to water in residualmaterial in RB Flask progressively became far lower than the minimumazeotropic boiling ratio itself for Benzene and Toluene. Presumably, itwas found that if one boils these solvents with water, with less solventto water ratio by weight than the minimum azeotropic boiling ratio, thena lot more solvent was found to be gone out per unit of water removed.

Example-6 Study of Above Azeotropic Boiling in Presence of Furnace Oil,with and without Bound and Free Water

In order to better understand behavior of solvents at boiling inpresence of furnace oil and modification thereof in presence of boundwater and free water thereafter, predefined weighed amounts of Tolueneand Furnace Oil in certain proportions were taken in the RB Flask infirst instance. Subsequently, Benzene, Toluene and Xylene were taken ata time with Furnace Oil based sludge containing bound water. Thereafter,each of the above solvents was taken at a time with furnace oil withdrinking water in a specific proportion in the RB Flask. This RB Flaskwas a part of Dean and Stark Apparatus that was heated in mantlefurnace. A condenser with chilled water supply was attached to the RBflask with supply of chilled water at 6° C. wherein the vapours ofsolvent and water were condensed. A Stop Cork at bottom of the receiverwas attached to periodically collect condensate and individually weighthe immiscible constituents after first separating them in a separatingflask. The temperature of material at near bottom in the RB Flask wascontinuously recorded using a digital thermometer.

TABLE 6.1 STUDY OF VARIATION IN BOILING POINT OF SOLVENTS IN PRESENCE OFFURNACE OIL AT 933 mbar SI. No. DESCRIPTION Benzene Toluene Xylene 1 Wt.of Furnace Oil Taken in — 300.41 — RB Flask (g) 2 Wt. of Solvent Takenin RB — 300.20 — Flask (g) 3 Initial Wt. Ratio of Solvent — 1.00 — toFurnace Oil 4 Observed Boiling Temperature — 110.93- — range at 933 mbar(° C.) 350.15 5 Wt. of Solvent Collected by — 305.96 — the end (g) 6 Wt.% Loss due to Evaporation, — 0.21 — etc.

TABLE 6.2 STUDY OF VARIATION IN BOILING POINT OF SOLVENTS IN PRESENCE OFFURNACE OIL & BOUND WATER AT 933 mbar SI. No. DESCRIPTION BenzeneToluene Xylene 1 Wt. of Sludge taken in RB Flask (g) 25.68 152.45 150.372 Wt. of Bound Water Present in Sludge (g) 12.79 75.94 74.90 3 Wt. ofFurnace Oil Present in Sludge (g) 12.89 76.51 75.47 4 Wt of Solventadded in RB Flask (g) 1024.04 759.46 415.39 5 Initial Wt. Ratio ofSolvent to Water present 80.06 10.00 5.55 6 Initial Wt. Ratio of Solventto Furnace Oil 79.44 9.92 5.50 Present 7 Observed Boiling TemperatureRange at 72.11-79.54 91.2-108.86 96.33-136.28 933 mbar (° C.) 8 InitialWt. Ratio of Solvent to Water 19.61 4.82 2.06 Collected 9 Final Wt.Ratio of Solvent to Water 122.66 104.67 10.35 Collected 10 Average Wt.Ratio of Solvent to Water 82.34 6.93 1.92 Collected 11 Wt. of TotalWater collected (g) 11.48 74.50 74.32 12 Wt. of Total Solvent collected(g) 945.32 516.07 142.68 13 Rate of Water Collection (g/min) 0.30 0.3314 Wt. Ratio of Solvent to Furnace Oil Left 5.67 3.44 3.59 over in RBFlask at the End of Experiment 15 Wt. of Solvent left over in RB 73.11236.52 270.72 Flask at the end of Experiment (g) 16 Wt. of Furnace Oilleft over in RB 12.89 76.51 75.47 Flask at the end of Experiment (g) 17Residual Water present in left over 1,551.59 2,614.04 530.01 Solvent cumFurnace Oil in ppm as determined by BTX Test 18 Wt. % Loss due toEvaporation, etc. 0.69 0.89 0.45

TABLE 6.3 STUDY OF VARIATION IN BOILING POINT OF SOLVENTS IN PRESENCE OFFURNACE OIL & FREE WATER AT 933 mbar SI. No. DESCRIPTION Benzene TolueneXylene 1 Wt. of Furnace Oil Taken in RB Flask (g) 151.88 150.00 153.31 2Wt of Solvent Taken in RB Flask (g) 304.40 600.01 460.26 3 Wt. of FreeWater added in RB Flask (g) 456.77 600.36 921.76 4 Initial Wt. Ratio ofWater to Solvent present 1.50 1.00 2.00 5 Initial Wt. Ratio of Solventto Furnace Oil 2.00 4.00 3.00 6 Observed Boiling Temperature Range at86.7-98.31 97.28-98.5 96.89-97.58 933 mbar (° C.) 7 Initial Wt. Ratio ofSolvent to Water 558.63 4.85 2.07 Collected 8 Final Wt. Ratio of Solventto Water 0.03 0.08 0.05 Collected 9 Average Wt. Ratio of Solvent toWater 2.26 2.38 1.05 Collected 10 Total Wt. of Water Collected (g)136.28 252.31 489.69 11 Total Wt. of Solvent Collected (g) 307.89 602.66464.66 12 Rate of Solvent Collection (g/min) 2.81 2.96 1.76 13 Wt. ofFurnace Oil Left behind in RB 148.39 147.35 148.91 Flask at the End ofExperiment (g) 14 Wt. of Free Water left behind in RB 315.54 343.86424.34 Flask at the end of Experiment(g) 15 Wt. % Loss due toEvaporation, etc. 0.54 0.31 0.50

It was observed that when Toluene and furnace Oil were taken inproportion of 50:50 by weight, they both being non-polar form asolution. It was observed that the boiling point of Toluene went up from110.8° C. since the boiling point of Furnace Oil is in the region of350° C. It was observed that when boiling began, Toluene preferentiallyboiled out as its boiling point was lot lower than that of Furnace Oil.The boiling point continuously rose as Toluene kept getting depleted ascan be clearly seen from Table 6.1.

As shown in Table 6.1, the boiling began at 110.93° C. at atmosphericpressure of 933 mbar. Boiling Point of pure Toluene is 110.80° C. at sealevel. Boiling ended at 350.15 that being the initial boiling point ofpure Furnace Oil. We actually collected back slightly more solvent thanwhat we added. At the end some Furnace Oil too came out.

It was observed that when solvent was added to any sludge for boilingout the bound water from hydrocarbons, there was yet another phenomenonworking apart from solvent helping to depress the boiling point of waterand vice versa which was vast reduction in viscosity of furnace oil thathelped in weakening of the forces that bind furnace oil to the boundwater. It was observed that the boiling point of bound water reduced byreducing viscosity itself.

As can be seen in Table 6.2, instead of pure furnace oil in case offurnace oil based sludge with 50 wt. % bound water, it was observed thatwater was held onto furnace oil so tightly that even on centrifuging itfor 10 minutes at 21,893 RCF, nil water was found to be separated fromthe furnace oil. Under such a circumstance, entire bound water gotremoved in temperature range of 91.2° C. to 108.86° C. through boilingalong with 69 wt. % of Toluene that was originally present. Averageweight ratio at which Toluene and Water came out was 6.93. As comparedto a mixture of pure water and toluene, here the boiling point rosetowards the end once ratio of Toluene to furnace oil dropped down belowa certain point. It was because with Toluene being in solution withfurnace oil, the latter raised the boiling point of former as seen inTable 6.1. Also wt. ratio of regressing solvent to water fell down from9.34 to 6.93 (as shown in Table 5.2) as entrainment became less sincehere the solvent was in solution with furnace oil.

Similarly, with Xylene, entire bound water got removed with 35 wt. %Xylene. It was observed that even the rate of water removal was betterat 0.33 g/minute as compared to 0.30 g/minute for Toluene.

Further, the temperature range was observed to be higher. It was in arange of about 96.33° C. to 136.28° C. This was because boiling point ofpure xylene was higher than that of toluene as can be seen from Table5.1. Interestingly, it was observed that the end boiling point roseclose to that of the boiling point of pure solvent. This was presumablybecause towards the end, with depletion of bound water, the left overmaterial in the RB flask became similar to the starting material as perTable 6.1. Here too the weight ratio of egressing solvent to water wasfound to be 1.92 which was lower than that 2.08 as indicated in Table5.2.

It was observed that rise in temperature occurred towards the end whenbound water was getting depleted. However, the use of multi-effectevaporator for boiling out water and solvent from hydrocarbons waspreferred. The multi-effect evaporator allowed material to be insections/vessels where ambient pressure and hence absolute temperaturewas low by the time boiling point rose. This successfully preventedthermal cracking.

It was observed that with benzene, entire bound water got removed with93 wt. % of Benzene. Benzene was found to be weakest in removing boundwater as per unit of bound water removed 82 units of benzene by weightwere required. Benzene was found to be the slowest amongst the solventshowever it was found to have an advantage that the entire process gotover by 80° C.

Here the boiling point range was found to vary from 72.11° C. to 79.54°C. It was observed that weight ratio of egressing benzene to water forboiling out pure water was 82.34 on an average, which was however morethan 61.97 as seen in Table 5.2. This showed here that the water wasindeed bound and not free. Therefore, a lot more benzene was required ashaving weakest ability to remove free water.

When solvent boiled out bound water, towards the end the quantum ofsolvent required to drive out a unit mass of water rose very sharplyalong rising boiling point. Also, it was observed that quantum ofrequired solvent went up partly because statistically it was thendifficult for egressing solvent vapours to encounter residual waterbefore emerging from furnace oil. It could also be partly because thelast bit of water could be most tightly bound to furnace oil. Boilingpoint also rose towards the end as there was no further depression ofboiling point of solvent present in solution with higher boiling furnaceoil. The depression in the boiling point of the solvent was availableearlier because of water being present was now no longer available.

A behavioral study of bound water in furnace oil based sludge afterbeing replaced with free water can be seen from Table 6.3. Here drinkingwater was added in the RB Flask in specific proportions with purefurnace oil and solvent wherein water added was in excess. It wasobserved here that instead the entire solvent went out and that too withfar lower boiling point range, leaving behind excess free water withfurnace oil. Free water was not found to be mixed with furnace oil andthat was removed by gravity based separation. It was observed that allthree solvents were entirely boiled out within a temperature range of97° C. to 99° C. except for benzene where boiling started from 86.7° C.and went up to 0.98.31° C. Interestingly, it was observed that the freewater drove out entire solvent from Furnace Oil and the final boilingpoint approached that of free water temperature and not that of solventtemperature. When free water drove out solvent, the weight ratio ofegressing solvent to water was a lot lower than minimum azeotropicboiling ratio. This was totally reverse of what happened when solventwas driving out entire bound water. While entire or slightly excesssolvent was removed only 30 wt. % of original free water left whileboiling out benzene, 42 wt. % free water left for boiling out tolueneand 53 wt. % water left for boiling out Xylene. As can be seen fromTable 6.3 that the weight ratio of egressing solvent to water was almostsame i.e. 2.26 and 2.38 for Benzene and Toluene respectively. A fractionof water left when removing Toluene due to addition of, less water forremoving toluene. Xylene was found to be more effective in removingbound water and Toluene was found to be more effective in removing freewater.

It was observed that the rate of solvent removal from the solution withhigher boiling hydrocarbons like furnace oil was a lot faster with freewater than the rate of bound water removal from same furnace oil insludge with same solvents. For example, Xylene removed bound water fromfurnace oil at the rate of 0.33 g/min. However, free water removedXylene from furnace oil at the rate of 1.76 g/min. This was because ofslow heating when removing bound water from furnace oil using xylene.This happened because water was held to furnace oil in sludge a lot moretightly than the binding strength between Xylene and furnace oil onaccount of their solubility.

Further, it was observed that when only traces of solvent were presentin Furnace Oil, a lot more water was required to remove a given mass ofsolvent towards the end. This was because with minuscule solvent left infurnace oil, the boiling point approached that of furnace oil or 350° C.although the solvent was being boiled out at less than 99° C.Statistically it was found lot more difficult for egressing water vapourto encounter solvent present within a far larger volume of furnace oilwhen only traces of solvent were present.

Accordingly, it was confirmed that the boiling point of solvents likeBenzene, Toluene and Xylene can be substantially depressed by addingfree water to the solution of hydrocarbons when these solvents werepresent in the solution with other hydrocarbons having substantiallyhigher boiling points. It was also confirmed that one can choose toremove either the entire water or entire solvent by varying theirinitial ratio in the mixture in case where furnace oil was present.

Example-7 Removal of Bound Water from Furnace Oil Sludges with 50 Wt. %Bound Water in it, by Boiling it with Azeotropic Solvents

In order to evaluate implications of using different quantity of varioussolvents on removal of bound water from. Furnace Oil Sludges with 50 wt.% Bound Water in it, predefined proportions of sludge and solvent byweight were taken in the RB flask of Dean and Stark Apparatus andfollowed by continuous heating thereof in the mantle heater whilecontinuously monitoring the temperature of material in RB Flask withdigital thermometer. The vapours of bound water and solvent werecollected in the receiver after condensing them with circulating coldwater 5° C. to 6° C. in the insulated condenser. The condensates wereout and collected in separating flask using the stop cork at the bottomof the receiver. After phase separation, water and solvent collectedwere individually weighed each time.

Removal of Bound Water with Xylene—

TABLE 7.1A REMOVAL OF BOUND WATER FROM FURNACE OIL SLUDGES BY VARYINGPROPORTIONS OF XYLENE AT 933 mbar SI. No. DESCRIPTION TEST 1 TEST 2 TEST3 TEST 4 1 Wt. of Sludge taken in RB Flask (g) 150.22 150.15 152.45150.90 2 Wt. % Water Present in Sludge 49.81 49.81 49.81 49.81 3 Wt. ofFurnace Oil Present in Sludge (g) 75.39 75.37 76.51 75.73 4 Wt. ofSolvent added in RB Flask (g) 123.52 138.69 155.87 171.07 5 InitialRatio of Solvent to Water by Wt. 1.65 1.85 2.05 2.28 6 Observed BoilingTemperature Range (° C.) 97.03-151.26 96.25-180.1 98.49-176.6695.76-162.68 7 Initial Wt. Ratio of Solvent to Water 2.05 2.04 2.01 2.10Collected 8 Final Wt. Ratio of Solvent to Water 4.11 1.44 4.24 8.52Collected 9 Average Wt. Ratio of Solvent to Water 1.79 1.86 1.92 2.07Collected 10 Wt. % Bound Water collected during 97.38 98.90 99.93 99.92Experiment inclusive of losses 11 Wt. % of Solvent collected during100.00 99.50 92.09 90.92 Experiment inclusive of losses 12 Wt. % ofFurnace Oil collected during 2.67 0.00 0.00 0.00 Experiment 13 AverageRate of Water Collection (g/min) 0.52 0.34 0.34 0.33 14 Wt. Ratio ofSolvent to Furnace Oil Left 0.00 0.01 0.16 0.46 over in RB Flask at theEnd of Experiment 15 Residual Water present in left over 25,998 10,880653 792 Solvent cum Furnace Oil in ppm as determined by BTX Test 16 Wt.% Loss due to Evaporation, etc. 2.87 2.39 1.04 0.91

TABLE 7.1B REMOVAL OF BOUND WATER FROM FURNACE OIL SLUDGES BY VARYINGPROPORTIONS OF XYLENE AT 933 mbar SI. No. DESCRIPTION TEST 1 TEST 2 TEST3 1 Wt. of Sludge taken in RB Flask (g) 153.66 151.67 153.05 2 Wt. %Water Present in Sludge 49.81 49.81 49.81 4 Wt. of Furnace Oil Presentin Sludge (g) 77.12 76.12 76.81 5 Wt. of Solvent added in RB Flask (g)191.45 226.71 268.04 6 Initial Ratio of Solvent to Water by Wt. 2.503.00 3.52 7 Observed Boiling Temperature Range (° C.) 98.71-146.0497.91-142.66 99.76-139.41 8 Initial Wt. Ratio of Solvent to Water 2.042.04 2.16 Collected 9 Final Wt. Ratio of Solvent to Water 1.71 2.90 8.50Collected 10 Average Wt. Ratio of Solvent to Water 1.83 2.07 2.48Collected 11 Wt. % Bound Water collected during 99.87 99.87 99.86Experiment inclusive of losses 12 Wt. % Solvent collected during 73.6068.81 71.49 Experiment inclusive of losses 13 Wt. % of Furnace Oilcollected during 0.00 0.00 0.00 Experiment 14 Average Rate of WaterCollection (g/min) 0.35 0.47 0.35 15 Wt. Ratio of Solvent to Furnace OilLeft 0.66 0.93 0.99 over in RB Flask at the End of Experiment 16Residual Water present in left over 1,297 1,314 1,432 Solvent cumFurnace Oil in ppm as determined by BTX Test 17 Wt. % Loss due toEvaporation, etc. 1.01 1.00 0.95

TABLE 7.1C REMOVAL OF BOUND WATER FROM FURNACE OIL SLUDGES BY VARYINGPROPORTIONS OF XYLENE AT 933 mbar SI. No. DESCRIPTION TEST 1 TEST 2 TEST3 1 Wt. of Sludge taken in RB Flask (g) 150.50 150.45 150.37 2 Wt. %Water Present in Sludge 49.81 49.81 49.81 3 Wt. of Furnace Oil Presentin Sludge (g) 75.53 75.51 75.47 4 Wt. of Solvent added in RB Flask (g)300.00 338.51 415.39 5 Initial Ratio of Solvent to Water by Wt. 4.004.52 5.54 6 Observed Boiling Temperature Range (° C.) 98.29-137.9496.64-137.68 96.33-136.28 7 Initial Wt. Ratio of Solvent to Water 2.142.02 2.06 Collected 8 Final Wt. Ratio of Solvent to Water 31.12 9.7410.35 Collected 9 Average Wt. Ratio of Solvent to Water 2.69 1.86 1.92Collected 10 Wt. % Bound Water collected during 99.97 99.92 99.95Experiment inclusive of losses 11 Wt. % Solvent collected during 67.5741.12 34.83 Experiment inclusive of losses 12. Wt. % of Furnace Oilcollected during 0.00 0.00 0.00 Experiment 13 Average Rate of WaterCollection (g/min) 0.35 0.33 0.33 14 Wt. Ratio of Solvent to Furnace OilLeft 1.29 2.64 3.59 over in RB Flask at the End of Experiment 15Residual Water present in left over 265 795 530 Solvent cum Furnace Oilin ppm as determined by BTX Test 16 Wt. % Loss due to Evaporation, etc.0.63 0.46 0.45Removal of Bound Water with Toluene—

TABLE 7.2 REMOVAL OF BOUND WATER FROM FURNACE OIL SLUDGES BY VARYINGPROPORTIONS OF TOLUENE AT 933 mbar SI. No. DESCRIPTION TEST 1 TEST 2TEST 3 1 Wt. of Sludge taken in RB Flask (g) 150.71 151.06 152.45 2 Wt.% Water Present in Sludge 49.81 49.81 49.81 3 Wt. of Furnace Oil Presentin Sludge (g) 75.64 75.82 76.51 4 Wt. of Solvent added in RB Flask (g)225.61 451.67 759.46 5 Initial Ratio of Solvent to Water by Wt. 3.006.00 10.00 6 Observed Boiling Temperature Range (° C.) 98.00-126.1089.06-146.44 89.28-108.87 7 Initial Wt. Ratio of Solvent to Water 5.455.29 4.82 Collected 8 Final Wt. Ratio of Solvent to Water 0.93 10.2414.87 Collected 9 Average Wt. Ratio of Solvent to Water 3.63 5.97 6.93Collected 10 Wt. % Bound Water collected during 86.40 98.23 99.74Experiment inclusive of losses 11 Wt. % Solvent collected during 100.0096.50 68.86 Experiment inclusive of losses 12 Wt. % of Furnace Oilcollected during 4.10 0.00 0.00 Experiment 13 Average Rate of WaterCollection (g/min) 0.36 0.33 0.30 14 Wt. Ratio of Solvent to Furnace OilLeft 0.00 0.21 3.09 over in RB Flask at the End of Experiment 15Residual Water present in left over 1,34,981 17,542 2,614 Solvent cumFurnace Oil in ppm as determined by BTX Test 16 Wt. % Loss due toEvaporation, etc. 1.61 0.52 0.89Removal of Bound Water with Benzene—

TABLE 7.3 REMOVAL OF BOUND WATER FROM FURNACE OIL SLUDGES BY VARYINGPROPORTIONS OF BENZENE AT 933 mbar SI. No. DESCRIPTION TEST 1 TEST 2 1Wt. of Sludge taken in RB Flask (g) 50.52 25.68 2 Wt. % Water Present inSludge 49.80 49.80 3 Wt. of Furnace Oil Present in Sludge (g) 25.3612.89 4 Wt. of Solvent added in RB Flask (g) 604.11 1024.04 5 InitialRatio of Solvent to Water by Wt. 24.01 80.06 6 Observed BoilingTemperature Range (° C.) 76.26-94.67 72.11-81.05 7 Initial Wt. Ratio ofSolvent to Water 26.93 19.61 Collected 8 Final Wt. Ratio of Solvent toWater 116.33 122.66 Collected 9 Average Wt. Ratio of Solvent to Water48.36 82.34 Collected 10 Wt. % Bound Water collected during 57.79 98.84Experiment inclusive of losses 11 Wt. % Solvent collected during 98.2896.25 Experiment inclusive of losses 12 Wt. % of Furnace Oil collectedduring 0.00 0.00 Experiment 13 Average Rate of Water Collection (g/min)0.04 0.02 14 Wt. Ratio of Solvent to Furnace Oil Left 0.41 2.98 over inRB Flask at the End of Experiment 15 Residual Water present in left over4,18,770 1,552 Solvent cum Furnace Oil in ppm as determined by BTX Test16 Wt. % Loss due to Evaporation, etc. 0.92 0.69

It was observed that in all above tables, entire water present in thesludge was bound water. It was observed that addition of 5.5 times theweight of water present in the sludge was must in case where Xylene wasused as solvent. However, it might be reduced to 3.5-4.5 times, withoutmuch rise in maximum temperature at the end of the experiment. It wasobserved that if Xylene was taken up to 3 times the weight of waterpresent then temperature at the end was not only high but also there wasresidual moisture in left over material. It was observed that additionof 10 times the weight of water present in sludge was must in case whereToluene was used as solvent. It was observed that moisture in residualFurnace Oil cum Solvent was low. It was observed that addition of 80times the weight of water present in sludge was must in case whereBenzene was used as a solvent. With this one can remove almost theentire bound water present in sludge.

As can be seen in Table 7-2, temperature rise was observed to be maximumwhen average weight ratio of Toluene to Water boiling out wasapproximately equal to original weight ratio that was present at thestart of the process inspite of which entire water cannot be removedfrom sludge. This was because under such a condition neither water wasable to boil out entire solvent nor the solvent was able to boil outentire water. However, then water may keep accumulating over time andmay boil out entire solvent from the mixture if average weight ratio ofsolvent to water boiling out was more than what was originally presentas in Test 1. On the contrary as seen in Test 3, it was seen that ifaverage weight ratio of solvent to water boiling out was far lower thanwhat was originally present, then solvent kept accumulating over timethereby ensuring that entire water got removed from sludge throughboiling. For Xylene, the worst weight ratio to have for solvent to waterwas 1.85. This was because the average weight ratio of solvent to waterboiling out was the same as what was present right in the beginning.

It was observed that final temperature was very high when one began theprocess by having the same weight ratio of solvent and water in mixtureas one would find on an average in the vapour phase. It was alsoobserved that it was very difficult to remove entire water or solventfrom sludge under that condition. It was observed that at least 1 wt. %to 1.5 wt. % water stayed back along with similar amounts of solvent.Removal of this residual amount of water and solvent was difficultinspite of massive rise in temperature.

When Xylene was added either 1.65 or 1.85 times the weight of waterpresent in furnace oil sludge with 50 wt. % water, at the end we foundthat our purpose was defeated. Instead of solvent removing entire boundwater, the bound water actually ended up removing entire solvent throughboiling. This was because the average egressing ratio of solvent towater by weight itself was 1.86 when xylene was 1.85 times the weight ofwater present. In the end it was observed that 0.54 wt. % Xylene wasleft behind with 1.09 wt. % water inspite of final temperature rising to180.1° C.

Similarly, it was observed that for Toluene and Benzene too there may bea cut off point for the amount of solvent added. If solvent added isless than that cut-off value then instead of solvent removing entirebound water one may find the bound water has boiled out the entiresolvent instead. For Toluene, that amount was observed to be between 5-6times the weight of water for furnace oil sludge with 50 wt. % water.For Benzene, that amount was about 80 times the weight of water infurnace oil sludge with 50 wt. % water.

It was observed that rate of water removal with Xylene was 0.33 g/min,with Toluene 0.30 g/min but with benzene it was only 0.02 g/min. Henceit was established that one may require a lot more benzene to take out aunit mass of water due to which the rate of water removal is so low.However, it was observed that only advantage with benzene was operativetemperature range which was found 72° C. to 80° C. as against 96° C. to138° C. for Xylene and 89° C. to 109° C. for Toluene. Here above ratesof water removal with Xylene, Toluene and Benzene were found to besmaller as compared to the rates of removal of free water with samesolvents (refer Table 5.2). It was observed that, the quantity of Xyleneegressing with unit weight of water was rising when initial ratio ofsolvent to water was in a range of about 1.65 to 4. Even for Toluene andBenzene, with more solvent added, more solvent found egressed per unitmass of water removed through boiling.

As can be seen from Test 3 in Table 7.1C that it was possible foraverage weight ratio of solvent to water boiling out to be lower thanboth the initial and final weight ratio in which they boil out. That wasbecause the minimum ratio in which they boil out was not at the verystart but somewhere soon after that. Also it can be seen from Table 7.1Cthat a very steep rise in the weight ratio in which they boil outtowards the end was observed when initial weight ratio of solvent towater was very high. Once that happened the end temperature stillincreased up, but then only up to the boiling point of pure solventunder ambient pressure and not well above it. Inspite of the weightratio of egressing solvent to water increased up steeply towards theend. It was observed that average weight ratio was not differ much thantheir initial weight ratio. This was because such a sharp rise in theirweight ratio and also in their boiling point was seen over a very shortperiod of time towards the very end of the process.

On the contrary, as can be seen from Table 7.1A and 7.1B, the finaltemperature reached exceeded the boiling point of pure xylene undersimilar ambient pressure when weight of xylene added is the range of1.85 to 3.0 times the weight of water present in sludge. Accordingly, itwas concluded that lower the ratio higher will be the final temperaturerise. This may be probably because when xylene was relatively less, itcannot adequately depress the boiling point of last bits of bound waterin furnace oil. Hence, it was confirmed that first the quantity ofsolvent added at the start has to be such that at the end of theprocess, for a given heating rate enough residual solvent remains backin furnace oil to adequately reduces its viscosity and also toadequately depress the boiling point of last bits of bound water infurnace oil.

Further it was observed that one must remove entire bound water withlarge amounts of solvent still remaining behind in residual furnace oilin order to get low operative temperatures that probably might havehelped in three ways. Firstly, furnace oil remained free flowing withvery small viscosity till the end. Secondly, the boiling point was notsignificantly raised till the end by presence of soluble furnace oilwith large fraction of residual solvent. Thirdly, it was easier for itto drive out traces of water towards the end with large presence ofresidual solvent.

It was observed that the left over weight ratio of solvent to oil wasobserved to be Minimum of 3.59, 3.09 and 2.98 for Xylene, Toluene andBenzene respectively for removing entire bound water from less viscousOil. However, to get above mentioned left over ratios one has to takeinitial wt. ratio of solvent to water/oil are 5.5, 10.0 and 80.0 forXylene, Toluene and Benzene respectively and follow optimally controlledrate of heating.

Example-8 Establishment of the Basis of Evaluating Quantity of Additionof Solvent

In order to establish the basis of evaluating how much solvent oneshould add was based on amount of water present in Sludge or the amountof hydrocarbons present therein. Accordingly, predefined proportions ofsludge and solvent by weight were taken in the RB flask of Dean andStark Apparatus and followed by continuous heating thereof in the mantleheater while continuously monitoring the temperature of material in RBFlask with digital thermometer. The vapours of bound water and solventwere collected in the receiver after condensing them with circulatingcold water at 5° C. to 6° C. in the insulated condenser. The condensateswere out and collected in separating flask using the stop cork at thebottom of the receiver. After phase separation, water and solventcollected were individually weighed each time.

TABLE 8.1 DETERMINING BASIS FOR ADDING XYLENE FOR REMOVAL OF BOUND WATERFROM FURNACE OIL SLUDGES AT 933 mbar SI. No. DESCRIPTION TEST 1 TEST 2TEST 3 TEST 4 1 Wt. of Sludge taken in RB Flask (g) 150.76 151.08 150.62151.42 2 Wt. % Water Present in Sludge 14.84 14.84 59.48 59.48 3 Wt. ofFurnace Oil Present in Sludge (g) 128.38 128.66 61.03 61.36 4 Wt. ofSolvent added in RB Flask (g) 414.65 707.70 492.74 339.34 5 InitialRatio of Solvent to Water by Wt. 18.53 31.57 5.50 3.77 6 Initial Ratioof Solvent to Furnace Oil 3.23 5.50 8.07 5.53 by Wt. 7 Observed BoilingTemperature Range (° C.) 96.34-139.53 93.02-140.12 96.25-135.3297.30-137.48 8 Initial Wt. Ratio of Solvent to Water 2.17 2.12 2.06 2.00Collected 9 Final Wt. Ratio of Solvent to Water 17.78 82.63 459.75 3.93Collected 10 Average Wt. Ratio of Solvent to Water 2.38 3.30 2.08 1.96Collected 11 Wt. % Water collected during 99.75 99.91 99.99 99.93Experiment inclusive of losses 12 Wt. % Solvent collected during 12.8610.61 37.24 50.97 Experiment inclusive of losses 13 Wt. % of Furnace Oilcollected during 0.00 0.00 0.00 0.00 Experiment 14 Average Rate of WaterCollection (g/min) 0.14 0.16 0.27 0.30 15 Wt. Ratio of Solvent toFurnace Oil Left 2.81 4.92 5.07 2.71 over in RB Flask at the End ofExperiment 16 Residual Water present in left over 500 159 85 1,037Solvent cum Furnace Oil in ppm as determined by BTX Test 17 Wt. % Lossdue to Evaporation, etc. 0.31 0.30 0.50 0.65

It was observed that the best results were obtained when residualsolvent to furnace oil ratio, by weight, at the end of the experimentwas high. In Test-3, where the above residual ratio was 5.07, leasttemperature rise was observed with maximum bound water removed withresidual moisture level being just 85 ppm. It was established, that itwould not matter whether one considers the weight of water or weight offurnace oil in sludge for evaluating the quantity of solvent to beadded.

As can be seen from Test Nos. 1 and 2, rate of water collection wasobserved to be significantly low when there was less water in FurnaceOil Sludges. This was inspite the fact that per unit mass of egressingsolvent more water was removed at that time. Apparently, water inFurnace Oil based Sludge was limited to the extent to which it candepress the boiling point of solvent.

Example-9 Evaluation of Efficacy of Process for Removal of Bound Waterfrom Different Furnace Oil Sludges

It was an aim of the experiment to evaluate efficacy of our Process forremoval of bound water from different Furnace Oil Sludges with varyingwater content with entire water present being only bound water.Accordingly, predefined proportions of sludge and solvent by weight weretaken in the RB flask of Dean and Stark Apparatus and followed bycontinuous heating thereof in the mantle heater while continuouslymonitoring the temperature of material in RB Flask with digitalthermometer. The vapours of bound water and solvent were collected inthe receiver after condensing them with circulating cold water at 5° C.to 6° C. in the insulated condenser. The condensates were out andcollected in separating flask using the stop cork at the bottom of thereceiver. After phase separation, water and solvent collected wereindividually weighed each time. Here bound water content in furnace oilsludges was varied from 2.15% to 84.94 wt. %.

TABLE 9.1A REMOVAL OF BOUND WATER FROM FURNACE OIL SLUDGES WITH VARYINGWT. % WATER BUT FIXED PROPORTION OF XYLENE AT 933 mbar SI. No.DESCRIPTION TEST 1 TEST 2 TEST 3 1 Wt. of Sludge taken in RB Flask (g)150.29 150.21 151.08 2 Wt. % Bound Water Present in Sludge 2.15 9.9114.84 3 Wt. of Furnace Oil Present in Sludge (g) 147.05 135.32 128.66 4Wt. of Solvent added in RB Flask (g) 809.39 745.87 707.70 5 InitialRatio of Solvent to Water by Wt. 249.81 50.09 31.56 6 Initial Ratio ofSolvent to Furnace Oil 5.50 5.51 5.50 by Wt. 7 Observed BoilingTemperature Range (° C.) 121.34-137.19 95.16-139.75 93.02-140.12 8Initial Wt. Ratio of Solvent to Water 3.36 2.24 2.12 Collected 9 FinalWt. Ratio of Solvent to Water 23.95 136.40 82.63 Collected 10 AverageWt. Ratio of Solvent to Water 14.79 2.90 3.30 Collected 11 Wt. % Watercollected during 107.52 98.70 99.91 Experiment inclusive of losses 12Wt. % Solvent collected during 6.50 5.92 10.61 Experiment inclusive oflosses 13 Wt. % of Furnace Oil collected during 0.00 0.00 0.00Experiment 14 Average Rate of Water Collection (g/min) 0.13 0.17 0.16 15Wt. Ratio of Solvent to Furnace Oil Left 5.15 5.18 4.92 over in RB Flaskat the End of Experiment 16 Residual Water present in left over 4841,428 159 Solvent cum Furnace Oil in ppm as determined by BTX Test 17Wt. % Loss due to Evaporation, etc. 0.12 0.17 0.30

TABLE 9.1B REMOVAL OF BOUND WATER FROM FURNACE OIL SLUDGES WITH VARYINGWT. % WATER BUT FIXED PROPORTION OF XYLENE AT 933 mbar SI. No.DESCRIPTION TEST 1 TEST 2 TEST 3 TEST 4 1 Wt. of Sludge taken in RBFlask (g) 153.07 150.37 150.62 150.12 2 Wt. % Bound Water Present inSludge 29.89 49.81 59.48 84.94 3 Wt. of Furnace Oil/Hydrocarbons 107.3175.47 61.03 22.61 Present in Sludge (g) 4 Wt. of Solvent added in RBFlask (g) 590.67 415.39 492.74 701.31 5 Initial Ratio, of Solvent toWater by Wt. 12.91 5.54 5.50 5.50 6 Initial Ratio of Solvent to FurnaceOil 5.50 5.50 8.07 31.02 by Wt. 7 Observed Boiling Temperature Range (°C.) 96.82-135.98 96.33-136.28 96.25-135.32 97.89-137.91 8 Initial Wt.Ratio of Solvent to Water 2.17 2.06 2.06 2.01 Collected 9 Final Wt.Ratio of Solvent to Water 41.90 10.35 459.75 57.89 Collected 10 AverageWt. Ratio of Solvent to Water 3.06 1.92 2.08 2.40 Collected 11 Wt. %Water collected during 99.97 99.93 99.99 99.98 Experiment inclusive oflosses 12 Wt. % Solvent collected during 33.84 34.69 37.24 43.56Experiment inclusive of losses 13 Wt. % of Furnace Oil collected during0.00 0.00 0.00 0.00 Experiment 14 Average Rate of Water Collection(g/min) 0.27 0.33 0.27 0.31 15 Wt. Ratio of Solvent to Furnace Oil Left4.19 3.59 5.07 17.51 over in RB Flask at the End of Experiment 16Residual Water present in left over 1,239 530 85 885 Solvent cum FurnaceOil in ppm as determined by BTX Test 17 Wt. % Loss due to Evaporation,etc. 0.30 0.45 0.50 0.49

It was observed that entire water in these sludges was bound water. Itwas understood that it was not possible to prepare sludge by mixingwater with furnace oil, with more than 60 wt. % or 61 wt. % water in itwith entire water being bound water. As explained earlier in Example-1,if one tries to mix 85 wt. % water with 15 wt. % furnace oil it forms amixture of sludge with bound water and slop oil. But still it wasindirectly possible to get furnace oil sludge with 85 wt. % bound waterin it. For that furnace oil sludge with 50 wt. % bound water was addedwith twice if its weight of solvent like xylene and then centrifuged for10 minutes at 21,893 RCF. Most furnace oil in sludge was moved out withsolvent leaving behind 14.5 wt. % of initial sludge cum solvent as astable viscous sludge containing 15 wt. % furnace oil with 85 wt. %bound water in that. This sludge was taken for Test 4 in Table 9.1B andthen removed bound water from therein.

In the range of 2 wt. % to 85 wt. % bound water, entire bound water wasremoved from the sludges without temperature exceeding 140.12° C. usingXylene as Solvent. Throughout Xylene added was either 5.5 times theweight of furnace oil or water present in sludge, whichever allowedadding more solvent thereto. In case where final temperature rose to140.12° C., the least water was obtained at 159 ppm left behind inresidual material at the end of the experiment.

It was also observed that the rate of water removal was distinctly lowwhen water content in sludge is 15 wt. % or lower. Rate of bound waterremoval was inversely proportional to binding strength of water tofurnace oil. This strength was higher when total water content waslower.

Further, it was found that the maximum rate of water removal was 0.33g/min. Yet this maximum rate of water collection was 4.15 times lowerthan 1.37 g/min, which was the rate of free water collection with Xylene(as shown in Table 5.2). Accordingly, it was proved that the waterremoved here was bound water and not free water.

It was also found that boiling point itself starts from 121° C. whenwater present in furnace oil sludge was only 2.15 wt. % whereas for allother cases is starts from 95° C. or 96° C. Also, on an average 14.79times of xylene egresses out when water present was 2.15 wt. % per unitmass of water removed. This high value might possibly be due to enormousquantity of Xylene being present. Normally, this weight ratio wasobserved to be varying from 3.3 to 1.92.

It was observed that more than 100 wt. % water got collected when waterpresent in furnace oil sludge is 2.15 wt. %. This may have happenedbecause error in BTX result was high especially with low moisture. Also,even otherwise BTX indicated a slightly lower value for water presentthan what was actually present.

Example-10 Removal of Bound Water from Furnace Oil Sludges Having 50 Wt.% Bound Water in it, by Varying the Rate of Heating, after AddingVarying Proportions of Solvents

It was an aim of the experiment to evaluate the impact of varying rateof heating, with different proportions of solvent added, on removal ofentire bound water from furnace oil sludges with 50 wt. % water in it.Accordingly, predefined proportions of sludge and solvent by weight weretaken in the RB flask of Dean and Stark Apparatus and followed bycontinuous heating thereof in the mantle heater while continuouslymonitoring the temperature of material in RB Flask with digitalthermometer. The vapours of bound water and solvent were collected inthe receiver after condensing them with circulating cold water at 5° C.to 6° C. in the insulated condenser. The condensates were out andcollected in separating flask using the stop cork at the bottom of thereceiver. After phase separation, water and solvent collected wereindividually weighed each time. However, except for the above mentionedfacts, the rate of heating was varied with the input voltage to mantleheater. This variation in heating rate meant that in most cases 25 ml ofcondensates in approximately 30, 20 or 10 minutes was collected.

TABLE 10.1 REMOVAL OF BOUND WATER FROM SLUDGES WITH 1.85 WT. RATIO OFXYLENE TO WATER BUT WITH VARYING RATE OF HEATING AT 933 mbar SI. No.DESCRIPTION TEST 1 TEST 2 TEST 3 1 Wt. of Sludge taken in RB Flask (g)153.90 151.63 150.15 2 Wt. % Water Present in Sludge 49.81 49.81 49.81 3Wt. of Furnace Oil Present in Sludge (g) 77.24 76.10 75.37 4 Wt. ofSolvent added in RB Flask (g) 141.98 140.86 138.69 5 Initial Ratio ofSolvent to Water by Wt. 1.85 1.86 1.85 6 Observed Boiling TemperatureRange (° C.) 95.46-179.31 97.70-173.19 96.25-180.1 7 Initial Wt. Ratioof Solvent to Water 2.01 2.06 2.04 Collected 8 Final Wt. Ratio ofSolvent to Water 1.21 0.52 1.44 Collected 9 Average Wt. Ratio of Solventto Water 1.86 1.83 1.86 Collected 10 Wt. % Water collected during 98.7199.50 98.90 Experiment inclusive of losses 11 Wt. % Solvent collectedduring 98.96 98.53 99.50 Experiment inclusive of losses 12 Wt. % ofFurnace Oil collected during 0.00 0.00 0.00 Experiment 13 Average Rateof Water Collection (g/min) 0.83 0.48 0.34 14 Average Rate of CondensateCollection 1.87 1.35 0.97 (g/min) 15 Wt. Ratio of Solvent to Furnace OilLeft 0.02 0.03 0.01 over in RB Flask at the End of Experiment 16Residual Water present in left over 12,817 4,993 10,880 Solvent cumFurnace Oil in ppm as determined by BTX Test 17 Wt. % Loss due toEvaporation, etc. 0.64 1.46 2.39

TABLE 10.2 REMOVAL OF BOUND WATER FROM SLUDGES WITH 2.25 INITIAL WT.RATIO OF XYLENE TO WATER BUT WITH VARYING RATE OF HEATING AT 933 mbarSI. No. DESCRIPTION TEST 1 TEST 2 TEST 3 1 Wt. of Sludge taken in RBFlask (g) 150.07 155.07 153.66 2 Wt. % Water Present in Sludge 49.8249.82 49.80 3 Wt. of Furnace Oil Present in Sludge (g) 75.32 77.82 77.124 Wt. of Solvent added in RB Flask (g) 187.31 193.30 191.45 5 InitialRatio of Solvent to Water by Wt. 2.50 2.50 2.50 6 Observed BoilingTemperature Range (° C.) 96.34-147.74 95.17-147.35 98.71-146.04 7Initial Wt. Ratio of Solvent to Water 1.98 1.95 2.04 Collected 8 FinalWt. Ratio of Solvent to Water 1.28 6.25 1.71 Collected 9 Average Wt.Ratio of Solvent to Water 2.02 1.81 1.83 Collected 10 Wt. % Watercollected during 99.97 99.96 99.87 Experiment inclusive of losses 11 Wt.% Solvent collected during 80.71 72.65 73.60 Experiment inclusive oflosses 12 Wt. % of Furnace Oil collected during 0.00 0.00 0.00Experiment 13 Average Rate of Water Collection (g/min) 1.01 0.47 0.35 14Average Rate of Condensate Collection 3.02 1.53 0.95 (g/min) 15 Wt.Ratio of Solvent to Furnace Oil Left 0.48 0.68 0.66 over in RB Flask atthe End of Experiment 16 Residual Water present in left over 266 3861,297 Solvent cum Furnace Oil in ppm as determined by BTX Test 17 Wt. %Loss due to Evaporation, etc. 0.96 0.95 1.01

TABLE 10.3 REMOVAL OF BOUND WATER FROM SLUDGES WITH 3.5 INITIAL WT.RATIO OF XYLENE TO WATER BUT WITH VARYING RATE OF HEATING AT 933 mbarSI. No. DESCRIPTION TEST 1 TEST 2 TEST 3 1 Wt. of Sludge taken in RBFlask (g) 150.86 150.71 153.05 2 Wt. % Water Present in Sludge 49.8149.81 49.81 3 Wt. of Furnace Oil Present in Sludge (g) 75.71 75.64 76.814 Wt. of Solvent added in RB Flask (g) 263.55 263.18 268.04 5 InitialRatio of Solvent to Water by Wt. 3.51 3.51 3.52 6 Observed BoilingTemperature Range (° C.) 98.29-143.2 97.12-134.91 99.76-139.41 7 InitialWt. Ratio of Solvent to Water 2.00 2.15 2.16 Collected 8 Final Wt. Ratioof Solvent to Water 11.02 1.68 8.50 Collected 9 Average Wt. Ratio ofSolvent to Water 2.14 1.86 2.48 Collected 10 Wt. % Water collectedduring 99.84 99.53 99.86 Experiment inclusive of losses 11 Wt. % Solventcollected during 61.44 53.00 71.49 Experiment inclusive of losses 12 Wt.% of Furnace Oil collected during 0.00 0.00 0.00 Experiment 13 AverageRate of Water Collection (g/min) 0.93 0.32 0.35 14 Average Rate ofCondensate Collection 2.86 1.12 1.00 (g/min) 15 Wt. Ratio of Solvent toFurnace Oil Left 1.34 1.64 0.99 over in RB Flask at the End ofExperiment 16 Residual Water present in left over 1,585 4,627 1,432Solvent cum Furnace Oil in ppm as determined by BTX Test 17 Wt. % Lossdue to Evaporation, etc. 0.72 0.68 0.95

TABLE 10.4 REMOVAL OF BOUND WATER FROM SLUDGES WITH 5.5 INITIAL WT.RATIO OF XYLENE TO WATER WITH VARYING RATE OF HEATING AT 933 mbar SI.No. DESCRIPTION TEST 1 TEST 2 TEST 3 1 Wt. of Sludge taken in RB Flask(g) 153.09 155.51 150.37 2 Wt. % Water Present in Sludge 49.81 49.8149.81 3 Wt. of Furnace Oil Present in Sludge (g) 76.83 78.05 75.47 4 Wt.of Solvent added in RB Flask (g) 419.48 426.63 415.39 5 Initial Ratio ofSolvent to Water by Wt. 5.50 5.51 5.54 6 Observed Boiling TemperatureRange (° C.) 95.74-137.26 95.16-137.45 96.33-136.28 7 Initial Wt. Ratioof Solvent to Water 2.03 2.04 2.06 Collected 8 Final Wt. Ratio ofSolvent to Water 7.93 23.35 10.35 Collected 9 Average Wt. Ratio ofSolvent to Water 2.20 2.34 1.92 Collected 10 Wt. % Water collectedduring 99.97 99.97 99.93 Experiment inclusive of losses 11 Wt. % Solventcollected during 39.65 42.69 34.69 Experiment inclusive of losses 12 Wt.% of Furnace Oil collected during 0.00 0.00 0.00 Experiment 13 AverageRate of Water Collection (g/min) 0.95 0.42 0.33 14 Average Rate ofCondensate Collection 2.69 1.18 0.93 (g/min) 15 Wt. Ratio of Solvent toFurnace Oil Left 3.30 3.13 3.59 over in RB Flask at the End ofExperiment 16 Residual Water present in left over 272 267 530 Solventcum Furnace Oil in ppm as determined by BTX Test 17 Wt. % Loss due toEvaporation, etc. 0.27 0.49 0.45

Xylene was added to furnace oil sludges with 50 wt. % Bound Water, in 4weight ratios, i.e. 1.85, 2.50, 3.50 and 5.50 with respect to waterpresent in Sludge. And then for each ratio the heating rate was varied.It was observed that impact of varying heating rate was marginal exceptfor weight ratios 1.85, 3.50 and 5.50. It was observed that medium rateof heating was necessary for weight ratio of 1.85 where water removalrate was 0.48 g/min or condensate removal rate was 1.35 g/min. It wasobserved that best results in terms of low residual moisture wereobtained in left over material with least rise in temperature. This wasfound to be a very sensitive ratio since residual solvent staying backin left over furnace oil was extremely small and hence slight variationtherein mattered a lot for removal of last bit of bound water withminimal temperature rise. At this rate of heating a little more watergot boiled out as compared to solvent, thereby allowing little moresolvent to accumulate and subsequently residual water rapidly boiled outat that elevated temperature.

Accordingly, it was established that for any amount of solvent added onemust always try to leave behind maximum amount of solvent in residualfurnace oil by allowing on an average least amount of solvent to boilout per unit mass of water removed through boiling if one wants toremove entire water from sludge at least temperature. However, slightincrease in mass of residual solvent staying behind till the end mighthave played a huge role in ensuring complete removal of water fromsludges at minimal temperature. It was observed that slowest rate ofheating was suitable for weight ratios of 3.50 and 5.5 although for 3.50there was not much difference between the medium and slow rates.However, for 5.5 the issue was clear. For ratio of 3.50, medium rate ofheating was not found to be feasible inspite of more solvent being leftbehind as more water was also left behind. Here the extra water leftbehind was significant to remove one has to increase the temperaturesubstantially and also consume large amounts of residual solvent.

However, it was observed that Xylene failed to boil out entire waterwhen weight of Xylene added was 1.65 times the weight of water insludge. Instead, water present in sludge boiled out entire Xylene. Thishappened because average weight ratio, in which solvent and water boilout was 1.79 (as can be seen from Test-1 in Table 7.1) which was a lothigher than initial weight ratio in which they were present prior toboiling. Here, it was established that the rate of heating might have tobe fast instead. Referring to Table Nos. 7.1A and 7.1C it was seen thatwhen Xylene added was 1.65 times the weight of water, water was boiledout at an average rate of 0.52 g/min as against a value of 0.33 g/minwhen weight xylene added was 5.5 times the weight of water present.Accordingly, it was established that the heating rate must be slow whenentire water has to be boiled out with preferred weight ratio of Xyleneand the heating rate must be fast when solvent has to be driven out.

Example-11 Impact of Severly Controlled Rate of Heating on Removal ofBound Water from Furnace Oil Sludges Using Solvents

A role of additional and severe controlled heating rate on removal oflast fractions of bound water present in sludges was studied.Accordingly, predefined proportions of sludge and solvent by weight weretaken in the RB flask of Dean and Stark Apparatus and followed bycontinuous heating thereof in the mantle heater while continuouslymonitoring the temperature of material in RB Flask with digitalthermometer. The vapours of bound water and solvent were collected inthe receiver after condensing them with circulating cold water at 5° C.to 6° C. in the insulated condenser. The condensates were out andcollected in separating flask using the stop cork at the bottom of thereceiver. After phase separation, water and solvent collected wereindividually weighed each time. This was except of the fact that towardsthe end of the process, when about 6 wt. % of water was left in sludgethe rate of heating was substantially reduced, even periodicallyallowing the temperature of mixture to fall by 3° C. to 10° C. The ideawas to hold the mixture within a fixed temperature range for much longertime, by firstly reducing and then by increasing temperature of residualmaterial within that range in small steps. Also this meant entirelystopping and re-starting the boiling process a large number of times.This allowed final traces of water to emerge from sludge with lots ofsolvent in sharp and short bursts. However, care was exerted to ensurethat condensates did not overflow from condenser top.

TABLE 11-A IMPACT OF SEVERELY CONTROLLING RATE OF HEATING AT END OF THEPROCESS WHEN USING XYLENE TO REMOVE BOUND WATER Failed Successful FailedSuccessful SI. Experiment Experiment Experiment Experiment No.DESCRIPTION # 1 # 1 # 2 # 2 1 Wt. of Sludge taken in RB Flask (g) 300.25150.22 301.18 150.90 2 Wt. % Bound Water Present in Sludge 49.91 49.8149.91 49.81 3 Wt. of Furnace Oil Present in Sludge (g) 150.39 75.39150.85 75.73 4 Wt. of Solvent added in RB Flask (g) 247.38 123.52 338.41171.07 5 Initial Ratio of Solvent to Water by Wt. 1.65 1.65 2.25 2.28 6Observed Boiling Temperature Range (° C.) 97.18-232.8 97.03-151.2697.41-307.31 95.76-162.68 7 Initial Wt. Ratio of Solvent to Water 2.152.05 2.04 2.10 Collected 8 Final Wt. Ratio of Solvent to Water 1.46 4.1129.53 8.52 Collected 9 Average Wt. Ratio of Solvent to Water 1.69 1.792.25 2.07 Collected 10 Wt. % Water collected during 98.50 97.38 98.8199.92 Experiment inclusive of losses 11 Wt. % Solvent collected during100.00 100.00 98.97 90.92 Experiment inclusive of losses 12 Wt. % ofFurnace Oil collected during 1.30 2.67 0.00 0.00 Experiment 13 AverageRate of Water Collection (g/min) 0.78 0.52 0.31 0.33 14 Average Rate ofCondensates Collection 1.20 1.83 2.30 0.50 (g/min) 15 Wt. Ratio ofSolvent to Furnace Oil Left — — 0.02 0.46 over in RB Flask at the End ofExperiment 16 Residual Water present in left over — 25,998.14 11,692792.29 Solvent cum Furnace Oil in ppm as determined by BTX Test 17 Wt. %Loss due to Evaporation, etc. 0.57 2.87 0.48 0.91

TABLE 11-B RESIDUAL WEIGHT RATIO OF XYLENE TO WATER IN RB FLASK AS THEPROCESS PROGRESSES WITH TIME Failed Successful Failed Successful SI.Experiment Experiment Experiment Experiment No. DESCRIPTION # 1 # 1 # 2# 2 1 Wt. Ratio of Solvent to 1.61 1.59 2.28 2.30 Water Left over in RBFlask After 1st Collection 2 Wt. Ratio of Solvent to 1.58 1.54 2.36 2.39Water Left over in RB Flask After 2nd Collection 3 Wt. Ratio of Solventto 1.55 1.48 2.50 2.54 Water Left over in RB Flask After 3rd Collection4 Wt. Ratio of Solvent to 1.53 1.39 2.68 2.81 Water Left over in RBFlask After 4th Collection 5 Wt. Ratio of Solvent to 1.49 1.24 3.07 3.37Water Left over in RB Flask After 5th Collection 6 Wt. Ratio of Solventto 1.44 0.42 3.99 5.08 Water Left over in RB Flask After 6th Collection7 Wt. Ratio of Solvent to 1.39 0.32 6.72 5.89 Water Left over in RBFlask After 7th Collection 8 Wt. Ratio of Solvent to 1.31 0.24 8.32 7.20Water Left over in RB Flask After 8th Collection 9 Wt. Ratio of Solventto 1.23 0.19 17.02 8.85 Water Left over in RB Flask After 9th Collection10 Wt. Ratio of Solvent to 1.12 — 2.40 9.71 Water Left over in RB FlaskAfter 10th Collection 11 Wt. Ratio of Solvent to 1.03 — — 10.19 WaterLeft over in RB Flask After 11th Collection 12 Wt. Ratio of Solvent to1.03 — — 9.47 Water Left over in RB Flask After 12th Collection 13 Wt.Ratio of Solvent to 1.10 — — — Water Left over in RB Flask After 13thCollection 14 Wt. Ratio of Solvent to 1.04 — — — Water Left over in RBFlask After 14th Collection 15 Wt. Ratio of Solvent to 1.16 — — — WaterLeft over in RB Flask After 15th Collection 16 Wt. Ratio of Solvent to1.11 — — — Water Left over in RB Flask After 16th Collection 17 Wt.Ratio of Solvent to 1.04 — — — Water Left over in RB Flask After 17th 18Wt. Ratio of Solvent to 0.81 — — — Water Left over in RB Flask After18th Collection 19 Wt. Ratio of Solvent to 0.49 — — — Water Left over inRB Flask After 19th Collection

As can be seen from Table 11-A, average rate of condensate collectionwas only 1.20 g/min as against a value of 1.83 g/min for successfulexperiment. Consequently higher amounts of xylene did not boil out, perunit mass of water removed through boiling. Hence as can be seen fromTable 11-B that the left over weight ratio of solvent to water wasslightly higher for failed experiment till 5th collection and at the topof that we did not severely slow down the heating rate towards the endof the process as explained above in procedure. Consequently, as can beseen from Tablel 1-B that due to high rate of heating we ended upboiling out solvent and water almost in equal ratio from 6th till 19thcollection.

It was observed that at least egressing solvent was slightly more thanthe water up to 10th collection and therefore the residual weight ratioof solvent to water at least kept falling slightly. But from 11th till17th collection they almost boiled out in equal proportion. Water cannotstay back with temperature of mixture approaching 232° C. More amount ofheat was fed at a rate faster than what could be consumed throughboiling. However, more solvent got removed through boiling than waterbecause of substantially slowed down rate of heating towards the end dueto which enough latent heat was not supplied for boiling out water.

In case where weight of Xylene added was 2.28 times the weight of waterpresent. Under this situation, weight ratio in which xylene and waterboil out was 2.07 when heated slowly such that the rate of condensatecollection was only 0.50 g/min. This allowed xylene to accumulateinstead by preferentially removing water from sludge through boiling.Here, firstly the overall rate of heating of the failed sample was highwith condensate collection rate being 2.30 g/min due to which it startedwith boiling out little more solvent per unit mass of water removed ascompared to slower rate of heating. Fortunately not much harm was donetill 3rd collection. In 4th and 5th collection more solvent left withfast heating. Additionally, towards the end the rate of heating was notslowed down for the failed sample. It was observed that the temperatureof residual furnace oil kept rising as the rate of heat supply farexceeded the requirement. With that then firstly water started going outrapidly since had the ability to soak up heat on account of its highlatent heat. Therefore, from 7th collection onwards, residual weightratio of solvent to water that remained behind kept rising and it roseup dramatically after 9th collection. After most water left then withhigh temperature rate of solvent boiling went up so dramatically, at thecost of water removal. Consequently, after 10th collection inspite ofthe fact that some water was still left behind, there was hardly anysolvent present to remove it. As can be seen in Table 11-A that at theend weight ratio of residual solvent to furnace oil fell down to 0.02.Taking out residual water from furnace oil was desirable for this ratioof initial xylene added by depressing its boiling point with the helpfrom large amounts of residual solvent. This was how inspite of havingexceeded 300° C. the entire water from furnace oil was removed.

Accordingly, it was ascertained that by opting for slow rate of heatingallowed less solvent to go out by end of 6th collection and consequentlya higher weight ratio of solvent to water was left behind in the RBFlask. Subsequently, heat closer to the required rate to boil out smallamounts of water and solvent from furnace oil was supplied bydrastically slowing the heating rate. From beginning of 7th till the endof 11th collection water boiled out only in slight preference to solventand not huge preference as earlier. Consequently, in the end lot ofsolvent remained behind in the RB Flask to drive out the last bit ofwater without furnace oil temperature rising only up to 163° C. and not307° C.

Finally, it was observed that with fast heating rate waterpreferentially boiled over solvent by a relatively large margin as itrequired a lot more latent heat for phase transformation. Also, it wasobserved that with ultra slow heating rate once again waterpreferentially boiled over solvent provided that the residual weightratio of left over solvent to water was high but by a relatively narrowmargin as reason being that the rate of heat supply was not the drivingfactor. Lastly, it was observed that the water preferentially boiled outwith very low rate of heating if solvent was present in higher quantitythan water.

Example-12 Removal of Bound Water from Diesel Sludges ContainingEmulsifier by Boiling it with Azeotropic Solvents

It was an aim of the experiment to evaluate the process of boiling outbound and unbound water with azeotropic solvents from diesel sludgescontaining emulsifier(s). Accordingly, predefined weight proportions ofsludge containing emulsifier and azeotropic solvent mixture were takenin the RB flask of Dean and Stark Apparatus and followed by continuousheating thereof in the mantle heater while continuously monitoring thetemperature of material in RB Flask with digital thermometer. Thevapours of bound water and solvent were collected in the receiver aftercondensing them with circulating cold water at 5° C. to 6° C. in theinsulated condenser. The condensates were out and collected inseparating flask using the stop cork at the bottom of the receiver.After phase separation, water and solvent collected were individuallyweighed each time.

TABLE 12 REMOVAL OF BOUND AND UNBOUND WATER FROM DIESEL SLUDGES USINGXYLENE & TOLUENE AT 933 mbar SI. No. DESCRIPTION TEST 1 TEST 2 1 Wt. ofSludge taken in RB Flask (g) 150.43 151.60 2 Wt. % of Total WaterPresent in Sludge 48.00 48.20 3 Wt. % of Bound Water present in Sludge2.91 2.90 4 Wt. % of Un-Bound Water present in Sludge 45.09 45.30 5 Wt.of Sodium Lauryl Sulphate Present in Sludge (g) 3.64 3.67 6 Wt. ofDiesel Present in Sludge (g) 74.58 74.86 7 Name of Solvent Used TolueneXylene 8 Wt of Solvent added in RB Flask (g) 722.30 402.36 9 InitialRatio of Solvent to Water by Wt. 10.00 5.51 10 Observed BoilingTemperature Range (° C.) 85.69-110.61 93.51-139.24 11 Initial Wt. Ratioof Solvent to Water Collected 6.00 2.15 12 Final Wt. Ratio of Solvent toWater Collected 73.02 76.50 13 Average Wt. Ratio of Solvent to WaterCollected 6.69 2.62 14 Wt. % Water collected during Experiment inclusiveof 100.00 99.91 losses 15 Wt. % Solvent collected during Experimentinclusive 67.04 48.05 of losses 16 Wt. % of Diesel collected duringExperiment 0.00 0.00 17 Rate of Water Collection (g/min) 0.47 0.74 18Wt. Ratio of Solvent to Diesel Left over in RB Flask 3.19 2.79 at theEnd of Experiment 19 Residual Water present in left over Solvent cum 0838 Diesel in ppm as determined by BTX Test 20 Wt. % Loss due toEvaporation, etc. 0.63 0.45

It was observed that only a tiny fraction of bound water was present inthe diesel sludge when an emulsifier like sodium lauryl sulphate wasadded thereto. In other words, only about 6 wt. % of total water presentgot so tightly bound to diesel that even on centrifuging it for 10minutes at 21,893 RCF none of that water was separated from diesel. Therate of water removal was about 2.2 times faster when using Xylene andabout 1.6 times faster when using Toluene in comparison to furnace oilsludge wherein the bound water was present in an amount of 49.81 wt. %,as Clearly seen in 7.1C and 7.2. This was because only a small fractionof water present was bound water.

It was observed that water collection rate was however significantlylower than that observed in Table 5.2 where Xylene and Toluene removedthe free water respectively at the rate of 1.37 g/min and 0.67 g/min. Itwas observed here that Xylene ended up removing entire water fromsludge, i.e. both bound and free water, as the weight of Xylene addedwas 5.51 times the weight of total water present.

It was observed that Toluene and Xylene both remove the bound andunbound water present in sludge inspite of the fact that most of thewater present was unbound water, still the final temperature shot up to110.61° C. and 139.24° C. respectively. This was because boiling pointsof these solvents cannot be depressed any further once entire water wasremoved. Once entire water was removed what was left was a solution ofsolvents and diesel, where diesel was having a slightly higher boilingpoint. It was observed that at that stage solvents began to boil out attheir respective boiling points under given ambient pressure withfurther application of heat. Inspite of the fact that final weight ratioof solvent to water collected was very high, the average ratio was stillvery small and only slightly higher than the initial weight ratioimplies that there was a brief and sharp rise in weight ratio of solventto water only towards the end of the process.

Example-13 Removal of Bound Water from ONGC Sludges, with 42 Wt. % BoundWater Therein, by Boiling with Azeotropic Solvents

It was an aim to evaluate implications of using different quantities ofvarious Solvents on removal of bound water from ONGC Viscous Sludgeswith 42.21 wt. % bound water in it. Accordingly, predefined weightproportions of ONGC sludge and azeotropic solvent mixture were taken inthe RB flask of Dean and Stark Apparatus and followed by continuousheating thereof in the mantle heater while continuously monitoring thetemperature of material in RB Flask with digital thermometer. Thevapours of bound water and solvent were collected in the receiver aftercondensing them with circulating cold water at 5° C. to 6° C. in theinsulated condenser. The condensates were out and collected inseparating flask using the stop cork at the bottom of the receiver.After phase separation, water and solvent collected were individuallyweighed each time.

ONGC Sludges with Bound Water—

TABLE 13.1 REMOVAL OF BOUND WATER FROM ONGC SLUDGES BY VARYINGPROPORTIONS OF SOLVENTS AT 933 mbar SI. No. DESCRIPTION TEST 1 TEST 2TEST 3 TEST 4 1 Wt. of Sludge taken in RB Flask (g) 150.58 154.75 150.17157.67 2 Wt. % Water Present in Sludge 42.21 42.21 42.21 42.21 3 Wt. ofHydrocarbons Present in Sludge (g) 87.02 89.43 86.78 91.12 4 Name ofSolvent Used Toluene Toluene Xylene Xylene 5 Wt. of Solvent added in RBFlask (g) 874.45 653.48 479.70 367.87 6 Initial Ratio of Solvent toWater by Wt. 13.76 10.00 7.57 5.53 7 Initial Ratio of Solvent toHydrocarbons by Wt. 10.05 7.31 5.53 4.04 8 Observed Boiling TemperatureRange (° C.) 93.10-108.38 90.10-108.93 101.32-136.67 97.60-137.06 9Initial Wt. Ratio of Solvent to Water Collected 4.98 4.92 2.05 2.04 10Final Wt. Ratio of Solvent to Water Collected 50.13 127.17 54.36 17.7511 Average Wt. Ratio of Solvent to Water Collected 6.06 6.03 2.53 2.2712 Wt. % Water collected during Experiment 99.94 99.85 99.97 99.78inclusive of losses 13 Wt. % Solvent collected during Experiment 44.3859.94 33.84 41.75 inclusive of losses 14 Wt. % Hydrocarbons collectedduring the 0.00 0.00 0.00 0.00 Experiment 15 Average Rate of WaterCollection (g/min) 0.26 0.45 0.34 0.90 16 Wt. Ratio of Solvent toHydrocarbons Left over 5.59 2.93 3.66 2.35 in RB Flask at the End ofExperiment 17 Residual Water present in left over Solvent 473 1,118 2391,614 cum ONGC Sludge in ppm as determined by BTX Test 18 Wt. % Loss dueto Evaporation, etc. 0.48 0.53 0.44 0.59

It was observed that when Toluene and Xylene were respectively added inweight ratio of 10 and 5.5 with respect to either the weight of water orhydrocarbons present in sludge thereby facilitating addition of maximumquantity of solvent. It was observed that slow rate of heating waspreferred for both Toluene and Xylene that left behind more solvent overhydrocarbons in the end. It was established that it was possible toremove almost entire bound water present in viscous ONGC sludge withoutallowing the temperature to rise above boiling points of these puresolvents by adding optimal quantum of solvent and with slow rate ofheating and under atmospheric pressure.

Example-14 Removal of Bound Water from Different Sludges by Combined Useof Azeotropic Solvents

It was an aim to evaluate implications of combining the use of Xyleneand Toluene on removal of Bound Water from ONGC and Furnace Oil sludgeswith respectively 42.21 wt. % and 49.81 wt. % bound water therein.Accordingly, predefined weight proportions of sludge and azeotropicsolvent mixture were taken in the RB flask of Dean and Stark Apparatusand followed by continuous heating thereof in the mantle heater whilecontinuously monitoring the temperature of material in RB Flask withdigital thermometer. The vapours of bound water and solvent werecollected in the receiver after condensing them with circulating coldwater at 5° C. to 6° C. in the insulated condenser. The condensates wereout and collected in separating flask using the stop cork at the bottomof the receiver. After phase separation, water and solvent collectedwere individually weighed each time.

TABLE 14.1 REMOVAL OF BOUND WATER FROM SLUDGES WITH COMBINED USE OFXYLENE and TOLUENE AT 933 mbar ONGC Furnace SI. Viscous Oil No.DESCRIPTION Sludge Sludge 1 Wt. of Sludge taken in RB Flask (g) 150.48151.16 2 Wt. % Water Present in Sludge 42.21 49.81 3 Wt. of HydrocarbonsPresent in Sludge (g) 86.96 75.86 4 Wt of Xylene added in RB Flask (g)239.28 207.34 5 Initial Ratio of Xylene to Water by Wt. 3.77 2.75 6Initial Ratio of Xylene to Hydrocarbons by Wt. 2.75 2.73 7 Wt of Tolueneadded in RB Flask (g) 435.75 376.53 8 Initial Ratio of Toluene to Waterby Wt. 6.86 5.00 9 Initial Ratio of Toluene to Hydrocarbons by Wt. 5.014.96 10 Observed Boiling Temperature Range (° C.) 91.74-118.6287.68-124.69 11 Initial Wt. Ratio of Solvent to Water Collected 4.184.45 12 Final Wt. Ratio of Solvent to Water Collected 145.62 67.63 13Average Wt. Ratio of Solvent to Water Collected 4.03 3.86 14 Wt. % Watercollected during Experiment inclusive of losses 99.74 99.89 15 Wt. %Solvent collected during Experiment inclusive of losses 38.06 49.69 16Wt. % Hydrocarbons collected during Experiment 0.00 0.00 17 Average Rateof Water Collection (g/min) 0.30 0.28 18 Wt. Ratio of Solvent toHydrocarbons Left over in RB Flask 4.81 3.87 at the End of Experiment 19Residual Water present in left over Solvent cum 1,893 1,097 Hydrocarbonsin ppm as determined by BTX Test 20 Wt. % Loss due to Evaporation, etc.0.64 0.65

These tests established that entire bound water can be removed from bothONGC as well as furnace oil sludges with combined use of Xylene andToluene as azeotropic solvents. Also, it was observed that the observedmaximum boiling temperature was almost mid way between maximum boilingtemperatures when using these solvents individually for the ONGC andfurnace oil sludges.

Example-15 Complete Removal of Solvents from Hydrocarbons by Heatingwith Free Water

It was an aim of the experiment to establish and evaluate the process ofboiling out entire solvents like Xylene, Toluene and Benzene fromfurnace oil at below 100° C. under atmospheric pressure of 933 mbar byadding free water therein. Accordingly, weighed amounts of furnace oil,solvent and water were added in specific proportions in the RB Flask ofDean and Stark Apparatus followed by heating them in a mantle heaterwhile periodically noting down the temperature of material in the RBFlask with digital thermometer. It was ensured that initial weight ratioof solvent to furnace oil was more than what was left behind in the RBFlask after removing entire bound water from furnace oil sludges. Thevapors of water and solvent that boiled out were condensed in aninsulated condenser where water was circulated at 5° C. to 6° C. Thecondensates were collected in a receiver thereby using a stop cork atbottom of the receiver to periodically drain out condensate inseparating flask while noting the time elapsed. After immediate phaseseparation the solvent and water collected were individually weighed. Atthe end material left in RB Flask was weighed and mass balance thereofwas performed.

TABLE 15.1A REMOVAL OF XYLENE FROM FURNACE OIL WITH VARYING PROPORTIONSOF FREE WATER AT 933 mbar SI. No. DESCRIPTION TEST 1 TEST 2 TEST 3 1 Wt.of Furnace Oil Taken in RB Flask (g) 151.60 153.86 152.46 2 Wt ofSolvent Taken in RB Flask (g) 910.51 923.44 915.03 3 Wt. of Free Wateradded in RB Flask (g) 682.98 923.82 1,374.44 4 Initial Wt. Ratio ofWater to Solvent 0.75 1.00 1.50 5 Initial Wt. Ratio of Solvent toFurnace Oil 6.00 6.00 6.00 6 Observed Boiling Temperature Range97.03-102.28 96.24-97.90 96.74-97.71 (° C.) 7 Initial Wt. Ratio ofSolvent to Water 2.18 2.21 2.04 Collected 8 Final Wt. Ratio of Solventto Water 0.52 0.08 0.03 Collected 9 Average Wt. Ratio of Solvent toWater 1.55 1.39 1.10 Collected 10 Total Wt. of Water Collected (g)588.19 669.49 837.39 11 Total Wt. of Solvent Collected (g) 913.99 928.82919.35 12 Average Rate of Solvent Collection 2.64 3.23 2.68 (g/min) 13Wt. of Furnace Oil Left behind in RB 148.12 148.48 148.14 Flask at theEnd of Experiment (g) 14 Wt. of Free Water left behind in RB Flask 87.03246.24 529.96 at the end of Experiment (g) 15 Wt. % Loss due toEvaporation, etc. 0.33 0.40 0.29

TABLE 15.1B REMOVAL OF XYLENE FROM FURNACE OIL WITH VARYING PROPORTIONSOF FREE WATER AT 933 mbar SI. No. DESCRIPTION TEST 1 TEST 2 TEST 3 TEST4 1 Wt. of Furnace Oil Taken in RB Flask 151.18 150.93 153.31 151.32 (g)2 Wt of Solvent Taken in RB Flask (g) 453.55 452.94 460.26 454.23 3 Wt.of Free Water added in RB Flask 454.02 679.55 921.76 1,135.85 (g) 4Initial Wt. Ratio of Water to Solvent 1.00 1.50 2.00 2.50 5 Initial Wt.Ratio of Solvent to Furnace 3.00 3.00 3.00 3.00 Oil 6 Observed BoilingTemperature Range 97.85-114.7 96.93-109.05 96.89-97.58 96.53-97.51 (°C.) 7 Initial Wt. Ratio of Solvent to Water 2.14 2.17 2.07 1.93Collected 8 Final Wt. Ratio of Solvent to Water 0.11 0.09 0.05 0.05Collected 9 Average Wt. Ratio of Solvent to 1.26 1.17 1.05 0.86 WaterCollected 10 Total Wt. of Water Collected (g) 364.39 392.49 489.69534.10 11 Total Wt. of Solvent Collected (g) 458.72 458.02 464.66 458.4712 Average Rate of Solvent Collection 2.16 2.82 1.76 2.16 (g/min) 13 Wt.of Furnace Oil Left behind in RB 146.01 145.85 148.91 147.08 Flask atthe End of Experiment (g) 14 Wt. of Free Water left behind in RB 84.09283.23 424.34 596.02 Flask at the end of Experiment (g) 15 Wt. % Lossdue to Evaporation, etc. 0.52 0.23 0.50 0.33

TABLE 15.2A REMOVAL OF TOLUENE FROM FURNACE OIL WITH VARYING PROPORTIONSOF FREE WATER AT 933 mbar SI. No. DESCRIPTION TEST 1 TEST 2 TEST 3 TEST4 1 Wt. of Furnace Oil Taken in RB Flask (g) 151.90 153.81 150.95 150.322 Wt of Solvent Taken in RB Flask (g) 456.13 461.66 453.01 450.42 3 Wt.of Free Water added in RB Flask (g) 228.62 346.72 453.70 675.64 4Initial Wt. Ratio of Water to Solvent 0.50 0.75 1.00 1.50 5 Initial Wt.Ratio of Solvent to Furnace Oil 3.00 3.00 3.00 3.00 6 Observed BoilingTemperature Range 96.15-121.44 96.89-103.86 96.40-98.30 95.90-97.6 (°C.) 7 Initial Wt. Ratio of Solvent to Water 6.00 6.72 5.11 4.73Collected 8 Final Wt. Ratio of Solvent to Water 0.21 0.18 4.15 1.98Collected 9 Average Wt. Ratio of Solvent to Water 2.77 2.89 2.35 1.87Collected 10 Total Wt. of Water Collected (g) 166.29 160.54 194.22241.15 11 Total Wt. of Solvent Collected (g) 461.03 464.68 456.24 452.1212 Average Rate of Solvent Collection 3.48 3.16 3.72 2.29 (g/min) 13 Wt.of Furnace Oil Left behind in RB 147.00 150.79 147.72 148.62 Flask atthe End of Experiment (g) 14 Wt. of Free Water left behind in RB Flask58.65 182.21 252.54 417.00 at the end of Experiment (g) 15 Wt. % Lossdue to Evaporation, etc. 0.44 0.41 0.66 1.37

TABLE 15.2B REMOVAL OF TOLUENE FROM FURNACE OIL WITH VARYING PROPORTIONSOF FREE WATER AT 933 mbar SI. No. DESCRIPTION TEST 1 TEST 2 TEST 3 1 Wt.of Furnace Oil Taken in RB Flask (g) 150.59 150.20 150.00 2 Wt ofSolvent Taken in RB Flask (g) 602.89 600.95 600.01 3 Wt. of Free Wateradded in RB Flask (g) 301.66 450.90 600.36 4 Initial Wt. Ratio of Waterto Solvent 0.50 0.75 1.00 5 Initial Wt. Ratio of Solvent to Furnace Oil4.00 4.00 4.00 6 Observed Boiling Temperature Range 95.17-111.7894.78-111.98 97.28-98.5 (° C.) 7 Initial Wt. Ratio of Solvent to Water6.61 4.97 4.85 Collected 8 Final Wt. Ratio of Solvent to Water 0.74 0.110.08 Collected 9 Average Wt. Ratio of Solvent to Water 5.06 2.48 2.38Collected 10 Total Wt. of Water Collected (g) 119.60 244.24 252.31 11Total Wt. of Solvent Collected (g) 605.84 606.01 602.66 12 Average Rateof Solvent Collection 6.42 4.04 2.96 (g/min) 13 Wt. of Furnace Oil Leftbehind in RB 147.64 145.14 147.35 Flask at the End of Experiment (g) 14Wt. of Free Water left behind in RB Flask 177.53 199.47 343.86 at theend of Experiment (g) 15 Wt. % Loss due to Evaporation, etc. 0.43 0.600.31

TABLE 15.3A REMOVAL OF BENZENE FROM FURNACE OIL WITH VARYING PROPORTIONSOF FREE WATER AT 933 mbar SI. No. DESCRIPTION TEST 1 TEST 2 TEST 3 TEST4 1 Wt. of Furnace Oil Taken in 151.64 150.45 151.88 154.18 RB Flask (g)2 Wt of Solvent Taken in RB 303.29 301.05 304.40 308.36 Flask (g) 3 Wt.of Free Water added in 151.70 301.53 456.77 616.83 RB Flask (g) 4Initial Wt. Ratio of Water to 0.50 1.00 1.50 2.00 Solvent 5 Initial Wt.Ratio of Solvent to 2.00 2.00 2.00 2.00 Furnace Oil 6 Observed Boiling77.39-135.43 80.85-105.00 86.70-98.31 82.27-97.82 Temperature Range (°C.) 7 Initial Wt. Ratio of Solvent to 54.92 67.90 558.63 64.73 WaterCollected 8 Final Wt. Ratio of Solvent to 0.16 0.08 0.03 0.03 WaterCollected 9 Average Wt. Ratio of Solvent 5.19 2.94 2.26 1.82 to WaterCollected 10 Total Wt. of Water Collected 59.23 103.51 136.28 170.95 (g)11 Total Wt. of Solvent Collected 307.61 304.68 307.89 312.14 (g) 12Average Rate of Solvent 3.55 2.77 2.81 2.28 Collection (g/min) 13 Wt. ofFurnace Oil Left 147.32 146.82 148.39 150.40 behind in RB Flask at theEnd of Experiment (g) 14 Wt. of Free Water left behind 87.66 192.59315.54 438.83 in RB Flask at the end of Experiment (g) 15 Wt. % Loss dueto 0.79 0.72 0.54 0.77 Evaporation, etc.

TABLE 15.3B REMOVAL OF BENZENE FROM FURNACE OIL WITH VARYING PROPORTIONSOF FREE WATER AT 933 mbar SI. No. DESCRIPTION TEST 1 TEST 2 TEST 3 TEST4 1 Wt. of Furnace Oil Taken in RB Flask 151.16 150.71 160.10 158.58 (g)2 Wt of Solvent Taken in RB Flask (g) 302.40 453.24 480.48 475.74 3 Wt.of Free Water added in RB Flask 912.29 453.21 720.95 951.49 (g) 4Initial Wt. Ratio of Water to Solvent 3.02 1.00 1.50 2.00 5 Initial Wt.Ratio of Solvent to Furnace 2.00 3.01 3.00 3.00 Oil 6 Observed BoilingTemperature Range 86.50-97.63 77.78-111.98 80.71-102.5 80.12-98.59 (°C.) 7 Initial Wt. Ratio of Solvent to Water 114.52 56.28 106.53 47.31Collected 8 Final Wt. Ratio of Solvent to Water 0.05 0.03 0.04 0.05Collected 9 Average Wt. Ratio of Solvent to Water 2.09 2.98 3.04 3.34Collected 10 Total Wt. of Water Collected (g) 145.64 152.88 159.83143.37 11 Total Wt. of Solvent Collected (g) 304.68 455.37 485.09 479.5512 Average Rate of Solvent Collection 2.76 3.06 3.46 3.79 (g/min) 13 Wt.of Furnace Oil Left behind in RB 148.88 147.58 155.49 154.77 Flask atthe End of Experiment (g) 14 Wt. of Free Water left behind in RB 761.77290.45 556.51 801.55 Flask at the end of Experiment (g) 15 Wt. % Lossdue to Evaporation, etc. 0.36 0.94 0.34 0.41

TABLE 15.4 COMPLETE REMOVAL OF 50:50 XYLENE AND TOLUENE FROM FURNACE OILWITH FREE WATER AT 933 mbar SI. No. DESCRIPTION TEST 1 1 Wt. of FurnaceOil Taken in RB Flask (g) 151.21 2 Wt of Toluene Taken in RB Flask (g)226.65 3 Wt of Xylene Taken in RB Flask (g) 227.16 4 Wt. of Free Wateradded in RB Flask (g) 682.02 5 Initial Wt. Ratio of Water to Xylene 3.006 Initial Wt. Ratio of Xylene to Furnace Oil 1.50 7 Initial Wt. Ratio ofWater to Toluene 3.00 8 Initial Wt. Ratio of Toluene to Furnace Oil 1.509 Observed Boiling Temperature Range 96.20-97.18 (° C.) 10 Initial Wt.Ratio of Solvent to Water 3.65 Collected 11 Final Wt. Ratio of Solventto Water 0.06 Collected 12 Average Wt. Ratio of Solvent to Water 1.35Collected 13 Total Wt. of Water Collected (g) 337.21 14 Total Wt. ofSolvent Collected (g) 456.61 15 Average Rate of Solvent Collection 1.58(g/min) 16 Wt. of Furnace Oil Left behind in RB 148.41 Flask at the Endof Experiment (g) 17 Wt. of Free Water left behind in RB Flask 339.40 atthe end of Experiment (g) 18 Wt. % Loss due to Evaporation, etc. 0.42

TABLE 15.5 COMPLETE REMOVAL OF SOLVENT FROM DIESEL WITH FREE WATER AT933 mbar SI. No. DESCRIPTION TEST 1 TEST 2 1 Wt. of Diesel Taken in RBFlask (g) 75.35 75.29 2 Name of Solvent taken Toluene Xylene 3 Wt ofSolvent Taken in RB 301.15 226.07 Flask (g) 4 Wt. of Free Water added inRB 303.20 454.56 Flask (g) 5 Initial Wt. Ratio of Water to Solvent 1.012.01 6 Initial Wt. Ratio of Solvent to Diesel 4.00 3.00 7 ObservedBoiling Temperature Range 92.54-97.24 96.50-97.27 (° C.) 8 Initial Wt.Ratio of Solvent to Water 5.17 1.98 Collected 9 Final Wt. Ratio ofSolvent to Water 0.82 0.61 Collected 10 Average Wt. Ratio of Solvent to3.57 1.15 Water Collected 11 Total Wt. of Water Collected (g) 86.33200.23 12 Total Wt. of Solvent Collected (g) 308.36 232.99 13 AverageRate of Solvent Collection 3.30 2.04 (g/min) 14 Wt. of Diesel Leftbehind in RB 68.14 68.37 Flask at the End of Experiment (g) 15 Wt. ofFree Water left behind in 211.77 250.15 RB Flask at the end ofExperiment (g) 16 Wt. % Loss due to Evaporation, etc. 0.75 0.55

TABLE 15.6 COMPLETE REMOVAL OF SOLVENT FROM ONGC VISCOUS DEWATEREDHYDROCARBONS WITH FREE WATER AT 933 mbar SI. No. DESCRIPTION TEST 1 TEST2 1 Wt. of ONGC Hydrocarbons Taken 86.07 86.09 in RB Flask (g) 2 Name ofSolvent taken Toluene Xylene 3 Wt. of Solvent Taken in RB Flask (g)378.73 322.13 4 Wt. of Free Water added in RB 379.16 644.34 Flask (g) 5Initial Wt. Ratio of Water to Solvent 1.00 2.00 6 Initial Wt. Ratio ofSolvent to ONGC 4.40 3.74 Hydrocarbons 7 Observed Boiling TemperatureRange 88.21-99.40 93.30-96.33 (° C.) 8 Initial Wt. Ratio of Solvent toWater 4.89 1.98 Collected 9 Final Wt. Ratio of Solvent to Water 0.080.03 Collected 10 Average Wt. Ratio of Solvent to 2.16 1.07 WaterCollected 11 Total Wt. of Water Collected (g) 177.25 304.88 12 Total Wt.of Solvent Collected (g) 382.89 326.77 13 Average Rate of SolventCollection 1.35 1.17 (g/min) 14 Wt. of ONGC Hydrocarbons Left 81.9181.45 behind in RB Flask at the End of Experiment (g) 15 Wt. of FreeWater left behind in 196.82 335.34 RB Flask at the end of Experiment (g)16 Wt. % Loss due to Evaporation, etc. 0.60 0.39

It was observed that the solvent cannot be entirely boiled out from thefurnace oil in absence of free water without the boiling point ofsolvent eventually rising up to 350° C. which was the initial boilingpoint for pure furnace oil. It was observed that in case where initialweight ratio of solvent to furnace oil as 1 or more, the solvent mightinvariably begin to boil at boiling point of pure solvent under similarpressure. But eventually with last bits of solvents boiling out, itsboiling point may approach that of pure furnace oil, that being 350° C.under atmospheric pressure of 933 mbar. For Toluene, this was clearlyseen in Table 6.1. However, it was seen that entire solvent can beboiled out from same furnace oil at less than 100° C. under a pressureof 933 mbar when free water was present in appropriate quantity. ForToluene, the boiling temperature range in present case was observed tobe 95.90 to 97.60° C. as seen from Table 15.2A. However, said range was110.93 to 350.15 without presence of free water as can be seen fromTable 6.1.

Further, it was observed that by adding Xylene 5.5 times the weight ofwater was present in the sludge when removing almost entire bound waterfrom the furnace oil sludge with 50 wt. % bound water therein. It wasseen that at, the end of the process weight ratio of Xylene to furnaceoil that was left behind was 3.59. Therefore, Xylene was added 6 timesthe weight of furnace oil and water added was 3 times the weight offurnace oil present. It was found that the boiling temperature was in arange of 96.24 to 97.90° C. in case where Xylene was added 6 times theweight of furnace oil and when water added was 1 times the initialweight of Xylene. It was found that the boiling temperature was in arange of 96.89° C. to 97.58° C. in case where Xylene was added 3 timesthe weight of furnace oil and water added was 2.00 times the initialweight of Xylene. Accordingly, it was ascertained that with lessproportion of solvent present more free water was needed to retainboiling point range of solvent below 100° C.

Further, as seen earlier at the end of bound water removal from abovefurnace oil sludge, the weight ratio of Toluene to furnace oil leftbehind was 3.09 as per table 7.2 and the weight ratio of benzene tofurnace oil left behind was 2.98 as per table 7.3. Hence, the processwas started by adding toluene 4 times the weight of furnace oil presentand then 3 times the weight of furnace oil present. A preferred initialweight ratio of free water to solvent was 1 in both cases. Withpreferred amount of free water, boiling point range for Toluene was97.28° C. to 98.50° C. and 96.40° C. to 98.30° C. respectively.

For benzene, the weight ratio Benzene was 3 times the weight of furnaceoil present and then 2 times the weight of furnace oil present. It wasseen that for 3 times benzene, preferred initial weight ratio of freewater to solvent was 2. However with 2 times benzene, preferred initialweight ratio of free water to solvent was 1.50 times instead. It wasseen that for both these preferred quantum of free water, the boilingtemperature range was 80.12-98.59° C. and 86.70-98.31° C. respectively.

Accordingly, it was ascertained that apparently there was no limitationon how much solvent could initially be present in furnace oil or type ofsolvent that could be present. However, entire solvent, whether benzene,toluene or xylene, could be removed through boiling at temperaturesbelow 100° C. by adding appropriate quantity of free water prior toheating. In fact, more the initial solvent present often less was theweight ratio of free water to solvent to be added. Further, it was seenthat increasing the quantum of free water beyond a certain limit, notonly the boiling point range for solvent fell down but also the quantityof solvent removed by unit mass of water boiling out also fell down.

In all cases more than 100 wt. % solvent was collected inspite of notconsidering some solvent that would have evaporated. That was becausetowards the end boiling was terminated after collecting some furnace oiltoo. Yet, it was seen that the final boiling point for solvent alwaysremained below 100° C. under 933 mbar. Along with solvent some furnaceoil was also collected only to ensure 100% removal of solvent.Therefore, furnace oil got slightly depleted. But once this solvent wasre-used there could be no further depletion of furnace oil.

It was seen that average weight ratio of solvent to free water collectedwas almost always less than average weight ratio of solvent to boundwater collected. The average collection temperature was also observed tobe less with preferred initial weight ratio of free water to solvent.

As seen in Table 15.4, when mixed solvents like xylene and toluene werepresent in furnace oil for instance in 50:50 ratio by weight, even theycan be entirely removed through boiling, at temperatures below 100° C.by ensuring that the weight of free water added was 1.50 times thecombined weight of initial solvents present.

However, as indicated in Table 15.4, when using mixed solvents to boilout entire bound water from sludges, the weight ratio of solvent tofurnace oil left behind at the end of the process was higher. Apparentlythere was no upper limit on how much solvent can be present in furnaceoil, as long as appropriate amount of free water was added prior toboiling.

As can be seen in Table nos. 15.5 and 15.6 that entire solvent presentcan be boiled out below the predefined temperature in case ofhydrocarbons such as free flowing Diesel or highly viscous dewateredONGC hydrocarbons and the like. In case where hydrocarbons have saltand/or ash or solids therein, then free water may perform an additionalfunction of de-salting and de-ashing apart from boiling out entire puresolvent for re-use or sale at temperatures below 100° C.

Example-16 Separation of Free Water and Furnace Oil

It was an aim to establish that free water can be separated from evenviscous hydrocarbons with time through gravity based settling orcentrifuge. Accordingly, weighed amounts of viscous furnace oil and freewater were taken in the RB flask and vigorously boiled for 15 minutes.Thereafter, in hot condition the contents were transferred in apre-heated and insulated separating flask. It was seen that bulk of freewater separated from immiscible furnace oil due to density differenceand gravity. Accumulated free water was removed after about 30 minutesfrom bottom of separating flask. The remaining material within theseparating flask, after removing its insulation, inside hot air oven for48 hours while maintaining its temperature at 90° C. Periodically, thecollected water was removed from bottom of separating flask. After 48hours, the remaining material was taken out, homogenized and then testedfor residual moisture using the BTX process. Subsequently, the boilingwas repeated and the hot material was transferred into un-insulatedseparating flask. The material was removed soon after removal of bulk offree water therefrom. The remaining furnace oil with 17.33 wt. %moisture was then taken out. Part of it was again heated and rest wasallowed to cool to a room temperature. Both these hot and cold fractionswere centrifuged for 5 minutes at 4,500 RCF. After centrifuge, 150 g offurnace oil was removed from top and tested for moisture through BTXProcess.

TABLE 16.1 SEPARATION OF FREE WATER FROM FURNACE OIL THROUGH GRAVITYBASED SETTLING SI. No. DESCRIPTION TEST 1 TEST 2 TEST 3 1 Wt. of FurnaceOil taken For Treatment (g) 1,000.18 1,000.28 1,001.66 2 Wt. of Watertaken for boiling (g) 1,000.58 1,001.61 1,000.23 3 Loss in weight duringboiling (g) 10.22 9.90 9.54 4 Pouring temperature of boiled mixture in98.27 97.93 98.95 insulated separating flask (° C.) 5 Loss in weightduring pouring in Separating 38.43 50.98 33.49 Flask (g) 6 Holding Time(min) 29.52 30.12 32.84 7 Temperature of Material at the time of 92.5093.20 93.80 removing Free Water from bottom (° C.) 8 Wt. of Watercollected from insulated 927.35 931.27 934.23 separating flask (g) 9Turbidity of above Water (NTU) 6.86 6.79 7.02 10 Remaining Wt. ofFurnace Oil + Free Water 1,024.76 1,009.74 1,024.63 in Separating Flask(g) 11 Holding Time in Oven (hrs) 48.00 48.00 48.00 12 Set Temperatureof Oven (° C.) 90.00 90.00 90.00 13 Wt. of Total Water CollectedPeriodically 47.62 40.24 41.84 from Separating Flask in 48 Hours 14Temperature of material Immediately after 83.40 84.1 83.50 taking outfrom Oven (° C.) 15 Wt. of Furnace oil Collected at the end of 957.57943.70 962.72 Experiment 16 Water Present in recovered Furnace Oil 3,5092,590 3,197 through BTX Process in ppm 17 Wt. of Material adhering tovarious surfaces 11.28 13.03 12.22 (g) 18 Wt. of Material lost due toEvaporation, etc. 8.29 10.33 7.85

TABLE 16.2 SEPARATION OF FREE WATER FROM FURNACE OIL BY HOT CENTRIFUGESI. No. DESCRIPTION TEST 1 TEST 2 1 Wt. of Furnace Oil + Free watertaken 1,043.49 1,141.14 For Centrifuge (g) 2 Wt. % Water present inabove 16.17 16.48 Material before Centrifuge 3 Temperature of materialbefore 87.88 90.01 Centrifuge (° C.) 4 Time taken in minutes to ReachMax. 2.80 2.75 Relative Centrifugal Force 5 Max. Relative CentrifugalForce at 4,500 4,500 which Centrifuge operated 6 Holding Time at Max.Relative 5.00 5.00 Centrifugal Force in minutes 7 Time taken in minutesto reduce RPM to 17.15 16.50 Zero 8 Total Residence Time in minutesinside 24.95 24.25 Centrifuge 9 Temperature of material after 59.9060.01 Centrifuge (° C.) 10 Residual Water present in Furnace 5,313 2,987Oil after Centrifuge as determined by BTX Process (ppm)

TABLE 16.3 SEPARATION OF FREE WATER FROM FURNACE OIL BY COLD CENTRIFUGESI. No. DESCRIPTION TEST 1 TEST 2 1 Wt. of Furnace Oil + Free watertaken For 1,135.83 1,128.83 Centrifuge (g) 2 Wt. % Water present inabove Material 17.33 17.28 before Centrifuge 3 Temperature of materialbefore Centrifuge (° C.) 32.10 30.90 5 Time taken in minutes to ReachMax. 2.90 2.65 Relative Centrifugal Force 6 Max. Relative CentrifugalForce at which 4500 4500 Centrifuge operated 7 Holding Time at Max.Relative Centrifugal 5.00 5.00 Force in minutes 8 Time taken tode-accelerate to zero RPM 16.35 16.25 9 Total Residence Time in minutesinside 24.25 23.90 centrifuge 10 Temperature of material afterCentrifuge (° C.) 33.88 32.98 11 Residual Water in Furnace Oil after1,17,895 1,12,688 Centrifuge as determined by BTX Process (ppm)

It was observed that, it was difficult to remove entire free water fromthe furnace oil being relatively viscous. It has to be heated to about99° C. to reduce its viscosity and then transferred hot with least fallin temperature, into a pre-heated and well insulated separating flask.On retaining there for about 30 minutes with less than 6° C. fall intemperature, about 94 wt. % to 95 wt. % of water drained out andcollected at the bottom of the separating flask. Further, the entireremaining material was heated at about 85-90° C. to obtain remaining 5wt. % to 6 wt. % water in next 48 hours. Finally it was observed thatless than 3,500 ppm residual water was left in Furnace oil afterperiodical removal of free water collected from bottom of the separatingflask. Accordingly, the parameters like the settling time required,maximum temperature needed for heating and residual water content inviscous hydrocarbon were established. It was seen that about 83 wt. %water was removed by gravity settling under hot condition followed bycentrifuging it for 5 minutes at 4,500 RCF. But still residual moisturein Furnace Oil fell down from 17.3 wt. % to 11.8 wt. %. However, hotcentrifuge with inlet temperature of 90° C. however worked whereinresidual moisture in Furnace Oil was reduced from 16.48 wt. % to 2,900ppm after centrifuging for 5 minutes at 4,500 RCF. It was evident thatthe recovered water was perfect for industrial use with turbidity valuesof 6 NTU to 7 NTU which was almost oil free that could be furtherprocessed for production of drinking water.

Example-17 Recovery of Pure Hydrocarbons, Bound Water, Solvent and thenFree Water from Petroleum Sludges

It was an aim to quantitatively and qualitatively retrieve back purehydrocarbons and entire water, inclusive of entire bound water, presentin various sludges and also retrieve back the entire solvent and freewater in accordance with process of the present invention.

Accordingly, weight fraction of bound and unbound water present insludges were firstly determined and then calculated amount of solventwas added therein followed by heating in a Dean and Stark Apparatususing Mantle Heater. Accordingly, entire bound and free water present insludge was removed with combined effect of solvent cum heat.Subsequently, entire water was condensed and collected along with partof solvent used. Further, a calculated amount of free water was added toresidual matter in RB Flask and once again heated using the sameapparatus. Subsequently, entire remaining solvent was removed andcollected along with some free water. Thereafter, the entire amount ofremaining free water from residual hydrocarbons was collected throughgravity separation after heating the hydrocarbons and retaining them ina hot condition for a predefined time period in case where hydrocarbonswere found viscous. Finally, both the waters and hydrocarbons wereevaluated for their quality/purity and in addition the quantitiesretrieved were evaluated by doing a mass balance study.

Furnace Oil Sludges—

TABLE 17.1 REMOVAL OF ENTIRE BOUND WATER FROM FURNACE OIL SLUDGES WITHBOUND WATER ALONE, BY BOILING WITH AZEOTROPIC SOLVENTS SI. No.DESCRIPTION TEST 1 TEST 2 1 Wt. of Sludge taken (Kg) 1.002 1.000 2 Wt. %of Bound Water Present in Sludge 49.81 49.81 3 Wt. % of Furnace OilPresent in Sludge 50.19 50.19 4 Name of Solvent added Xylene Toluene 5Wt. of Solvent added (Kg) 2.742 4.981 6 Initial Wt. Ratio of Solvent toWater 5.50 10.00 Present 7 Initial Wt. Ratio of Solvent to Furnace Oil5.46 9.92 Present 8 Observed Boiling Temperature Range 96.5-136.989.4-108.3 (° C.) 9 Initial Wt. Ratio of Solvent to Water 2.06 4.82Collected 10 Final Wt. Ratio of Solvent to Water 10.36 14.87 Collected11 Average Wt. Ratio of Solvent to Water 1.92 6.93 Collected 12 Wt. %Water collected during Experiment 99.96 98.13 inclusive of losses 13 Wt.% Solvent collected during 34.81 67.95 Experiment inclusive of losses 14Wt. Ratio of Solvent to Furnace Oil Left 3.55 3.11 over in RB Flask atthe End of Experiment 15 Residual Water present in left over 410 1,119Solvent cum Furnace Oil in PPM as determined by BTX Test

TABLE 17.2 REMOVAL OF ENTIRE SOLVENTS FROM DE-WATERED FURNACE OIL BYUSING FREE WATER SI. No. DESCRIPTION TEST 1 TEST 2 1 Wt. of De-WateredFurnace Oil 0.503 0.502 present in RB Flask (kg) 2 Wt. of SolventPresent in RB Flask 1.7835 1.561 (kg) 3 Wt. of Free Water added in RBFlask 3.569 1.561 (kg) 4 Initial Wt. Ratio of Water to Solvent 2.00 1.005 Observed Boiling Temperature Range 96.89-97.58 96.40-98.30 (° C.) 6Initial Wt. Ratio of Solvent to Water 2.07 5.12 Collected 7 Final Wt.Ratio of Solvent to Water 0.05 4.14 Collected 8 Average Wt. Ratio ofSolvent to 1.05 2.35 Water Collected 9 Total Wt. of Free Water Collected1.896 0.67 (kg) 10 Total Wt. of Solvent Collected (kg) 1.788 1.565 11Wt. of Furnace Oil left behind in RB 0.499 0.498 Flask at the end ofExperiment (kg) 12 Wt. of Free Water left behind in RB 1.634 0.86 Flaskat the end of Experiment (kg) 13 Wt. % Loss due to Evaporation, etc.0.51 0.66

TABLE 17.3 REMOVAL OF ENTIRE FREE WATER FROM SOLVENT AND BOUND WATERFREE FURNACE OIL SI. No. DESCRIPTION TEST 1 TEST 2 1 Total Wt. ofFurnace Oil & Free Water 2.142 1.367 taken for further processing (kg) 2Total Wt. of Water collected by Gravity 1.587 0.844 Separation in 48hours when retained at 85 to 90° C. (kg) 3 Wt. of Furnace Oil recovered(kg) 0.493 0.492 4 Moisture in Furnace Oil as per BTX 3,320 4,291 (ppm)5 Turbidity of recovered Free Water (NTU) 4.8 3.9 6 Wt. % Material lostdue to Evaporation, 2.86 2.23 adhering to various surfaces, etc.

TABLE 17.4 TEST RESULTS SI. No Description TEST 1 TEST 2 1 Wt. % FurnaceOil recovered 98.90 98.81 2 Calorific value of recovered Furnace Oil10,182 10,169 (kcal/kg) 3 Calorific value of original Furnace Oil 10,17310.173 (kcal/kg) 4 Wt. % Solvent recovered for Re-use 99.54 99.13inclusive of that lost by adhering to glasswares 5 Wt. % Bound Waterrecovered for Re-use 99.95 98.13 6 Wt. % Free Water recovered for Re-use96.60 97.18

TABLE 17.5 QUALITY OF RECOVERED BOUND WATER FROM FURNACE OIL SLUDGE UNITSL. TEST OF PERMISSIBLE NO. PARAMETERS METHOD MEASUREMENT LIMITS RESULTS1 Colourhazen IS: 3025 P4 Hazen Max 15 1.00 Units 2 Odour IS: 3025 (Part— Agreeable Agreeable 5) - 1983 Part 3 pH at 25° C. IS: 3025 (Part —6.5-8.5 7.5 11) - 1983 4 Taste IS: 3025 (Part 7 — Agreeable Agreeable &8) - 1984 5 Turbidity IS: 3025 (Part NTU Max 5 1.4 10) - 1984 6Dissolved solids at IS: 3025 (Part mg/L Max 2000 46.00 180° C. 16) -1984 7 Aluminium as Al APHA 3125 mg/L Max 0.2 <0.005 8 Ammonia (as TotalIS: 3025 P34 mg/L Max 0.5 <0.05 Ammonia-N) 9 Anionic surface Annex K ofIS: mg/L Max 1.0 <0.02 active agents (as 13428 MBAS) 10 Barium as BaAPHA 3125 mg/L Max 0.7 <0.005 11 Boron as B EPA 200.8 mg/L Max 1.0<0.005 12 Calcium as Ca IS: 3025 (Part mg/L Max 200 8.80 40) - 1991 13Chloramines (as IS: 3025 P26 mg/L Max 4.0 <0.05 Cl₂) 14 Chloride as ClEPA 300.1 mg/L Max 1000 2.77 15 Copper as Cu APHA 3125 mg/L Max 1.5<0.005 16 Fluoride as F EPA 300.1 mg/L Max 1.5 <0.1 17 Free residual IS:3025 (Part mg/L Min 1.0 <0.1 Chlorine 26) - 1986 18 Iron as Fe APHA 3125mg/L Max 0.3 <0.005 19 Magnesium as Mg IS: 3025 (Part mg/L Max 100 2.4346) - 1994 20 Manganese as Mn APHA 3125 mg/L Max 0.3 <0.005 21 MineralOil clause 6 of mg/L Max 0.5 Absent IS: 3025 Part 39 - 1991 22 Nitrateas NO₃ EPA 300.1 mg/L Max 45 10.12 23 Phenolics as IS: 3025 Part 43 -mg/L Max 0.002 <0.001 C₆H₅OH 1992 24 Selenium as Se APHA 3125 mg/L Max0.01 <0.001 25 Silver as Ag APHA 3125 mg/L Max 0.1 <0.005 26 Sulphate asSO₄ EPA 300.1 mg/L Max 400 2.60 27 Sulphide as H₂S IS: 3025 (Part mg/LMax 0.05 <0.02 29) - 1986 28 Total Alkalinity as IS: 3025 P-23 mg/L Max600 40.00 CaCo₃ 29 Total Hardness as IS: 3025 P21 mg/L Max 600 32.00CaCo₃ 30 Zinc as Zn APHA 3125 mg/L Max 15 <0.005 31 Cadmium as Cd APHA3125 mg/L Max 0.003 <0.001 32 Cyanide as CN IS: 3025 P-34 mg/L Max 0.05<0.02 33 Lead Pb APHA 3125 mg/L Max 0.01 <0.005 34 Mercury as Hg EPA200.8 mg/L Max 0.001 <0.0005 35 Molybdenum as APHA 3125 mg/L Max 0.070.002 Mo 36 Nickel as Ni APHA 3125 mg/L Max 0.02 <0.005 37 Total Arsenicas APHA 3125 mg/L Max 0.05 <0.001 38 Total Chromium as APHA 3125 mg/LMax 0.05 <0.005 Cr 39 Chemical Oxygen SM: 5002-B mg/L 15.00 Demand 40Total Organic IS: 3025 (part mg/L 17.65 Carbon NO. 44) 41 BiochemicalAPHA-5310-B mg/L 4.00 Oxygen Demand - 3 days at 27° C. 42 Coliforms IS1622: 1981 MPN/100 ml <10 <2 43 Escherichia Coli IS 1622: 1981 MPN/100ml Absent Absent

TABLE 17.6 REMOVAL OF ENTIRE BOUND WATER FROM ONGC VISCOUS SLUDGES WITHBOUND WATER ALONE, BY BOILING WITH AZEOTROPIC SOLVENTS SI. No.DESCRIPTION TEST 1 TEST 2 1 Wt. of Sludge taken (kg) 1.000 1.001 2 Wt. %Bound Water Present in 42.21 42.21 Sludge 3 Wt. % Hydrocarbon Present in57.79 57.79 Sludge 4 Name of Solvents added Xylene Toluene 5 Wt. ofSolvent added (kg) 3.195 5.815 6 Initial Wt. Ratio of Solvent to 7.5713.76 Water added 7 Initial Wt. Ratio of Solvent to 5.53 10.05Hydrocarbon added 8 Observed Boiling Temperature 101.21-136.6193.08-108.32 Range (° C.) 9 Initial Wt. Ratio of Solvent to 2.09 5.04Water Collected 10 Final Wt. Ratio of Solvent to 54.31 50.13 WaterCollected 11 Average Wt. Ratio of Solvent to 2.54 6.08 Water Collected12 Wt. % Water collected during 99.64 99.30 Experiment inclusive oflosses 13 Wt. % Solvent collected during 33.31 43.89 Experimentinclusive of losses 14 Wt. Ratio of Solvent to 3.65 5.52 HydrocarbonsLeft over in RB Flask at the End of Experiment 15 Residual Water presentin left over 329 290 Solvent cum Hydrocarbons in ppm as determined byBTX Process

TABLE 17-7 REMOVAL OF ENTIRE SOLVENTS FROM DE-WATERED HYDROCARBONS BYUSING FREE WATER SI. No. DESCRIPTION TEST 1 TEST 2 1 Wt. of De-WateredHydrocarbons 0.578 0.579 present in RB Flask (kg) 2 Wt of SolventPresent in RB Flask 2.107 3.193 (kg) 3 Wt. of Free Water added in RBFlask 4.215 3.197 (kg) 4 Initial Wt. Ratio of Water to Solvent 2.00 1.005 Observed Boiling Temperature Range 93.25-96.30 88.18-99.26 (° C. ) 6Initial Wt. Ratio of Solvent to Water 2.01 4.93 Collected 7 Final Wt.Ratio of Solvent to Water 0.03 0.07 Collected 8 Average Wt. Ratio ofSolvent to 1.05 2.14 Water Collected 9 Total Wt. of Free Water Collected1.994 1.49 (kg) 10 Total Wt. of Solvent Collected (kg) 2.114 3.198 11Wt. of Hydrocarbons Left behind in 0.572 0.574 RB Flask at the End ofExperiment (kg) 12 Wt. of Free Water left behind in RB 2.194 1.659 Flaskat the end of Experiment (kg) 13 Wt. % Loss due to Evaporation, etc.0.40 0.62

TABLE 17.8 SEPARATION OF ENTIRE FREE WATER FROM HYDROCARBONS SI. No.DESCRIPTION TEST 1 TEST 2 1 Total Wt. of Hydrocarbons & Free water 2.7652.233 (kg) 2 Wt. of Free Water collected by Gravity 2.144 1.608separation while material was kept in oven at 90° C. for 48 hrs. (kg) 3Wt. of Hydrocarbons recovered (kg) 0.559 0.564 4 Moisture inHydrocarbons as per BTX 2,579 3,421 (ppm) 5 Turbidity of recovered FreeWater (NTU) 4.6 4.0 6 Wt. % Material loss due to Evaporation, 2.27 2.71adhering various surfaces, etc.

TABLE 17.9 TEST RESULTS SI. No. DESCRIPTION TEST 1 TEST 2 1 Wt. %Hydrocarbons recovered 97.72 98.32 2 Calorific value of recovered 10,62910,641 Hydrocarbons (kcal/kg) 3 Wt. % Solvent recovered for Re-use 99.2798.8 inclusive of materials adhering on glasswares 4 Wt. % Bound Waterrecovered for re-use 99.64 99.30 5 Wt. % Free Water recovered for re-use97.73 96.93

TABLE 17.10 REMOVAL OF ENTIRE WATER FROM FREE FLOWING DIESEL SLUDGESWITH BOUND AND FREE WATER BOTH, BY BOILING WITH AZEOTROPIC SOLVENTS SI.No. DESCRIPTION TEST 1 TEST 2 1 Wt. of Diesel Sludge taken (kg) 1.0031.005 2 Wt. % Water Present in Sludge 48.20 48.00 3 Wt. % Sodium LaurylSulphate Present in Sludge 2.42 2.45 4 Wt. % Diesel Present in Sludge49.38 49.55 5 Name of Solvents added Xylene Toluene 6 Wt. of Solventadded (kg) 2.660 4.824 7 Initial Wt. Ratio of Solvent to Water Present5.50 10.00 8 Initial Wt. Ratio of Solvent to Diesel Present 5.37 9.69 9Observed Boiling Temperature Range (° C.) 93.45-139.19 85.60-110.53 10Initial Wt. Ratio of Solvent to Water Collected 2.18 6.09 11 Final Wt.Ratio of Solvent to Water Collected 76.50 73.02 12 Average Wt. Ratio ofSolvent to Water Collected 2.64 6.66 13 Wt. % Water collected duringExperiment 99.99 100.00 14 Wt. % Solvent collected during Experiment48.05 67.04 15 Wt. Ratio of Solvent to Diesel Left over in 2.78 3.17 RBFlask at the End of Experiment 16 Residual Water present in left overSolvent 96 0.00 cum Diesel in ppm as determined by BTX Test

TABLE 17.11 REMOVAL OF ENTIRE SOLVENTS FROM DE-WATERED DIESEL BY USINGFREE WATER SI. No. DESCRIPTION TEST 1 TEST 2 1 Wt. of De-Watered DieselPresent 0.495 0.498 in RB Flask (kg) 2 Wt. of Solvent Present in RBFlask 1.377 1.578 (kg) 3 Wt. of Free Water added in RB Flask 2.767 1.594(kg) 4 Initial Wt. Ratio of Water to Solvent 2.01 1.01 5 ObservedBoiling Temperature 96.42-97.21 92.42-97.18 Range (° C.) 6 Initial Wt.Ratio of Solvent to Water 2.01 5.19 Collected 7 Final Wt. Ratio ofSolvent to Water 0.60 0.82 Collected 8 Average Wt. Ratio of Solvent to1.13 3.49 Water Collected 9 Total Wt. of Free Water Collected 1.2230.453 (kg) 10 Total Wt. of Solvent Collected 1.383 1.585 (kg) 11 Wt. ofDiesel Left behind in RB 0.489 0.491 Flask at the End of Experiment (kg)12 Wt. of Free Water left behind in RB 1.522 1.112 Flask at the end ofExperiment (kg) 13 Wt. % Loss due to Evaporation, etc. 0.48 0.78

TABLE 17.12 SEPARATION OF FREE WATER FROM DIESEL SI. No. DESCRIPTIONTEST 1 TEST 2 1 Total Wt. of Diesel & Free water (kg) 2.011 1.603 2Total Wt. of Water collected by Gravity 1.495 1.101 separation (kg) 3Wt. of Diesel recovered (kg) 0.470 0.471 4 Moisture in Diesel as per BTX(PPM) 21 72 5 Turbidity of recovered Free Water (NTU) 2.9 2.1 6 Wt. %Material loss due to Evaporation, 2.31 1.94 adhering to varioussurfaces, etc.

TABLE 17.13 TEST RESULTS SI. No Description TEST 1 TEST 2 1 Wt. % ofDiesel recovered 96.12 95.92 2 Calorific value of Recovered Diesel11,023 11,020 (kcal/kg) 3 Calorific value of Original Diesel 11,00211,002 (kcal/kg) 4 Wt. % Solvent recovered for Re-use 98.10 99.75inclusive of materials adhering on Glasswares 5 Wt. % Water recoveredfrom Sludge 99.99 99.99 for reuse 6 Wt. % Free Water recovered for reuse98.2 99.01

Referring to tables 17.1-17.13, the total furnace oil that was presentin sludges retrieved was about 99 wt. %. This was inspite of the factthat a tiny fraction thereof got removed along with solvent collected.It was seen that the furnace oil retrieved was having about 3,806 ppm ofresidual moisture on an average as against original water content of2,100 ppm therein. Inspite of slightly higher water content therecovered furnace oil was observed to have a calorific value of 10, 176kcal/kg on an average as against the value of 10,172 kcal/kg fororiginal furnace oil.

Further, it was observed that about 98 wt. % of the hydrocarbons presentin Sludges were retrieved for ONGC hydrocarbons with 3,000 ppm ofresidual water on an average thereby having a calorific value which wasobserved to be 10,635 kcal/kg on an average. Further, it was observedthat about 96 wt. % diesel was retrieved on an average from Dieselsludges with average moisture level of 47 ppm and with an averagecalorific value of 11,021 kcal/kg as against to that of original dieselhaving calorific value 11,002 kcal/kg.

Further, it was observed that more than 99 wt. % bound water wasretrieved from furnace oil sludges with an excellent quality as can beclearly seen in table 17-5. The bound water recovered from ONGC sludgerecovery was observed to be 99.5 wt. %. The bound water recovered fromdiesel sludges was observed to be 100 wt. %.

Further, it was observed that more than 99 wt. % solvent was retrievedfrom furnace oil sludges. The solvent recovery for ONCG sludges wasobserved to be 99 wt. %. The solvent recovery for Diesel Sludges wasfound to be 98.9 wt. %.

Further, it was observed that free water retrieved from furnace oilsludges was about 96.5 wt. % on an average. The free water recovery forONGC sludges was 97.3 wt. %. The free water recovery for diesel basedsludges was found to be 98.6 wt. %. The free water obtained was in largein quantity and was under process for more than 48 hours with multiplesteps.

Example-18 Preparation of Oil Coated Sand and Deoiling of Sand UsingXylene Followed by Recovery of Pure Sand, Oil and Xylene

In order to study removal of hydrocarbons from solids Furnace Oil andONGC free flowing Oil coated sand samples were prepared. These sandsamples were treated using solvent like Xylene and thereafterquantitatively and qualitatively the recovery of sand, oils, Xylene andwater was evaluated. Firstly, weighed amounts of oils into weighed sandwhich was water washed, completely dried and very clean. After mixingoils into sand, the oil coated sand samples were washed in separatebatches of Xylene. Progressively, oil was moved from sand into Xylene.The washing was stopped once turbidity value and colour of pure Xylenedid not change much from its original state after last washing cycle ofthe sand. At this stage, sand was believed to be coated with Xylenewhile entire oil on the sand was believed to be moved into spent Xylene.The Xylene coated sand was slowly heated beyond the boiling point ofXylene in Buchi Rotary Evaporator. The vapors of Xylene were condensedand collected. Subsequently, Xylene oil mixture was heated with freewater to boil out entire Xylene with some free water in Dean and Starkapparatus thereby leaving behind oil with a fraction of free water.Subsequently, free water was removed through gravity separation whilekeeping entire material at 85° C.-90° C. for 48 hours. Finally recoveredsand, oil and free water were evaluated for quality followed by doingmass balance thereof.

TABLE 18.1 PRODUCTION OF OILY SAND SI. No. Description Expt-1 Expt-2 1Wt. of sand taken (kg) 1.00 1.00 2 Final Turbidity of water 1.21 1.15after washing of sand with water (NTU) 3 Wt. % loss of pure sand on 0.160.16 heating it at 815° C. for 1 hr. 4 Type of Oil added ONGC FREEFURNACE FLOWING OIL HYDROCARBONS 5 Wt. of Oil added to Sand 0.10 0.15(kg) 6 Total Mass of Oily Sand 1.10 1.15 (kg) 7 Wt. % oil present inOily 9.21 13.16 Sand

TABLE 18.2 REMOVAL OF OIL FROM OILY SAND BY WASHING WITH XYLENE SI. NoDescription Expt-1 Expt-2 1 Wt. Ratio of Xylene to Oily sand in 1.5 2.0each washing 2 Wt. of Xylene added in each washing 1.65 2.31 (kg) 3Minimum number of washings 4 7 required to wash out Oil 4 Total amountof Xylene used (kg) 7.300 15.240 5 Turbidity of xylene after finalwashing 0.463 0.501 of sand (NTU) 6 Turbidity of pure Xylene (NTU) 0.4210.421

TABLE 18.3 RECOVERY OF SAND, OIL AND XYLENE SI. No Description Expt-1Expt-2 Step 1: Recovery of Xylene sticking from sand after washings 1Total Wt. of sand & Xylene (kg) 1.27 1.98 2 Wt. of sand after Dried at160° C. (kg) 1.00 1.001 3 Wt. of Solvent collected as condensate 0.260.96 (kg) Step 2: Separation of Xylene from Oil Step 2a: Addition ofWater & Boiling 4 Wt. of Solvent & Oil taken (kg) 6.76 13.72 5 Wt. ofFree Water added (kg) 13.51 27.44 6 Max. Temp in ° C. while Boiling 97.597.8 7 Wt. of Solvent collected as condensate 6.75 13.72 (kg) 8 Wt. ofWater collected as condensate 7.18 14.58 (kg) 9 Wt. of Free Water & Oilremaining 6.34 12.87 (kg) Step 2b: Separation of Oil and Water bygravity separation & Periodic removal of separated water by keepingmaterial in oven at 90° C. for 48 hours 10 Wt. of Oil recoveredinclusive of 0.10 0.15 sticking on glassware (kg) 11 Moisture in Oilafter Step 2b as per 3,420 3,123 BTX (ppm) 12 Turbidity of recoveredFree Water after 4.2 3.6 Step 2b (NTU)

TABLE 18.4 TEST RESULTS SI. No Description Expt-1 Expt-2 1 Wt. % sandrecovered inclusive of 99.94 99.93 materials sticking on glasswares 2Turbidity of water after washing of 0.542 0.589 de-oiled sand (NTU) 3Wt. % loss of dried sand after heating 0.11 0.11 it at 815° C. for 1hour 4 Wt. % Solvent recovered for Re- 96.25 96.41 use inclusive ofmaterials sticking on glasswares 5 Moisture in recovered Solvent as per144 163 BTX (ppm) 6 Wt. % Oil recovered inclusive of 99.07 98.95materials sticking on glasswares 7 Moisture in recovered Oils as per3,420 3,123 BTX (ppm) 8 Calorific value of recovered Oil 10,580 10,164(kcal/kg) 9 Calorific value of original Oil 10,652 10,173 (kcal/kg) 10Wt. % Free Water recovered for re- 98.08 98.37 use inclusive of watersticking on glasswares

Referring to tables 18.1-18.4, it was observed that recovery of sand wasabout 100 wt. %. Further, it was seen that recovery of oils was about 99wt. % and recovery of solvent was 96 wt. % inclusive of all weighablematerials sticking on various surfaces. Even free water employed to boilout solvent from oils was retrieved up to 98 wt. %. The sand recoveredwas oil free and whose wt. % loss on heating at 815° C. for 1 hour was0.11 wt. % which was less than 0.16 wt. % for oil free, fresh sand. Theturbidity was observed to be only 0.56 NTU as against the value of 1.2NTU for water that was used for washing fines free fresh sand. Therecovered ONGC free flowing oil was having only 3,420 ppm of residualmoisture with a calorific value of 10,580 kcal/kg as against residualmoisture of 3,900 ppm and calorific value of 10,652 kcal/kg for originalONGC Oil. It was seen that the recovered furnace oil was having residualmoisture of about 3,123 ppm with calorific value of 10,164 kcal/kg asagainst original furnace oil having residual moisture of 2100 ppm andcalorific value of 10,173 kcal/kg. It was seen that the recoveredSolvent had barely 153 ppm moisture in it on an average as against 40ppm moisture in original Xylene used.

Further, it was observed that amount of Xylene required to wash unitmass of oil coated sand depends on both the type of oil that coats thesand and the amount of oil coating the sand. The weight of Xylenerequired was about 7 times the weight of oily sand for removing 9.2 wt.% ONGC free flowing oil. The weight of Xylene required was instead about13 times for completely de-oiling the sand that contain 13.12 wt. %Furnace oil.

Example-19 Effect of Time Related Change in Turbidity Values of SlopOils

It was an aim to evaluate change in turbidity values of slop oils withtime. Further, it was an aim to observe which hydro-carbons fragmenteasily to produce stable slop oils. Also, it was an aim to study whysolvents behave differently from oils. Accordingly, slop oils wereprepared with different oils and solvents. These oils/hydrocarbons wereadded to water in varying parts per million and then vigorouslyfragmented in high shear mixer at 10,000 RPM over varying time.Subsequently, a representative sample was subjected to Turbidity test atwavelength of 455 nm with Hach Turbidity Meter. The turbidity readingswere measured in NTU (Normal Turbidity Unit) thereby taking turbidityvalues of these slop oils at regular intervals of time till they reachednear constant values.

TABLE 19.1 DESCRIPTION OF OILS & SOLVENTS USED FOR PREPARATION OF SLOPOILS DESCRIPTION CALORIFIC SI. OF HYDRO- Wt. % WATER Wt. % ASH VALUE NO.CARBONS PRESENT CONTENT (kcal/kg) 1 Coconut Oil 0.04 Wt. % Free 0.018,972 Water 2 ONGC Oil 0.39 Wt. % Free 0.88 10,633 Water 3 ONGC Viscous42.21 Wt. % 8.60 5,213 Hydrocarbons Bound Water 4 Diesel 0.01 Wt. % Free0.00 11,002 Water 5 Furnace Oil 0.21 Wt. % 0.23 10,173 Bound Water 6Xylene 0.004 Wt. % Free 0.00 10,205 Water 7 Toluene 0.004 Wt. % Free0.00 10,074 Water 8 Benzene 0.002 Wt. % Free 0.00 9,995 Water

It was observed that unlike Xylene and Toluene, Benzene failed to easilyfragment or remain fragmented into fine droplets even over short periodsof time with vigorous stirring in water and therefore Benzene wasbelieved to be not as suitable as Xylene and Toluene for mopping upultra-fine oil droplets from slop oils. This was indicated by itsturbidity values of 8 to 12 NTU as shown in FIG. 7 and FIG. 8. Theturbidity values of transparent liquids were indicative of populationdensity of droplets having diameters of order of 455 nm per unit volumeof liquid.

Slop Oils contain all sizes of oil droplets. Amongst them, ultra-fineswere found to be most difficult to mop up. Benzene was found little lesseffective than Xylene and Toluene when removal of ultra-fine dropletswas an object. It was found that very large droplets of solvents werebetter suited for removing all oil droplets, other than a fraction ofthose which were ultra-fine in size. Large droplets of solvents workfaster in removing bulk of the oil present. As these were the ones thatswept away and then carried with them large numbers of smaller oildroplets while rising up due to buoyancy.

It was seen that only a tiny fraction of total oil present resided indifficult-to-remove ultra-fine droplets. However, the ultra finedroplets were found contributing towards turbidity to a certain extent.Hence, relatively very large droplets of solvents like those of Benzeneor even Xylene and Toluene cannot lower turbidity of slop oils beyond apoint when they were hand mixed into slop oils, with mild mixing inparticular.

Accordingly, it was established that one must use solvents thatimmediately fragment into ultra-fine droplets and then quickly coalesceinto very large sized droplets to derive advantages of all sizes ofsolvent droplets. Although both Xylene and Toluene were found good forprocessing Slop Oils, however, Xylene was found to be better thanToluene since it initially fragmented into a lot smaller sized droplets.

FIGS. 9-12 as against FIGS. 13-20, bear testimony to a statement thatgood solvents coalesce very rapidly unlike hydrocarbons present in theslop oils. Most dispersed hydrocarbons, other than few like Diesel, tookdays to coalesce and reduce their turbidity. However, the turbidityvalues of Toluene and Xylene fell down in hours. Also, it was seen thatthe turbidity values of Xylene and Toluene fell down sharply withincreasing concentration, unlike those of most hydrocarbons. This can beclearly seen by comparing FIG. 9 with FIG. 14. It was seen that, withsolvents, higher concentration did not lead to higher population densityof ultra-fine droplets. Instead it triggered instant coalescence.

Further, it was seen that turbidity values of Toluene and Xylene droppeddown steeply by increasing mixing time at 10,000 RPM. This was contraryto what happened with most hydrocarbons, including Diesel. Forhydrocarbons like Diesel and ONGC Oil, increased time of mixing causedfurther fragmentation with increased population density of ultra-finedroplets. But for coconut oil it initially narrowed variations indroplet size. The slop oil may be made lot more stable by making dropletsize more uniform with which turbidity values do not change with time.

For solvents, however, more mixing resulted in unstable rise in surfaceenergy which then triggered immediate coalescence. It was seen that byextending mixing time from 1 to 5 minutes at 10,000 RPM and for 2500ppm, the turbidity value of Toluene fell down from 1,570 and 4,682 NTUto 54 and 874 NTU. It was established that solvent coalesced rapidlythat helped them to grow into large droplets quickly that reduced dragwhich then helped them to rise rapidly due to buoyancy. Here, Toluenewas observed to surpasses Xylene.

In case of Diesel, it was seen that Diesel too got fragmented initiallybut not as much as Toluene and Xylene. It was also seen that Diesel wasextremely fast as compared to other hydrocarbons with regard tocoalescence, but still not found as fast as that of Toluene and Xylene.After 13 mins of mixing at 10,000 RPM turbidity values for 2,500 ppmDiesel Slop Oil was 3,852 NTU, while for same ppm & RPM, turbidityvalues of Toluene and Xylene after 5 mins of mixing alone were 54 and874 NTU respectively. However, as clearly seen in FIG. 21, Diesel basedSlop Oils were found easiest to be processed for recovery of oil andclean water due to rapid coalescing nature.

In case with 2,500 ppm coconut oil in water having 3 mins of mixing at10,000 RPM gave very stable slop oil. But this stability vanished withfurther increase in mixing time. Accordingly, it was established thatfor very stable coconut oil based slop, oils, one must begin withvigorous mixing before beginning to process them for recovery of pureoil and water.

It appeared that highly stable ONGC free flowing oil based slop oilscould be formed either by extending their time of mixing or byincreasing their hydrocarbon concentration. However, it was founduncertain that to what extent that value depends on color of slop oiland to what extent on oil droplet size.

Example-20 Effect of Heat on Turbidity of Slop Oils

It was an aim to understand the effect of heat on turbidity of slop oilswhen heated in an oven at 85 to 95° C. for few hours or subjected tovigorous boiling for five minutes. Accordingly, low and medium turbidityslop oils were prepared with Coconut Oil and Free Flowing ONGC Oil asexplained below in Table Nos. 20.1 and 20.3. Only the turbidity valueswere measured for low turbidity slop oils immediately before and afterheating. Additionally, Coconut Oil based slop oils with medium turbiditywere subjected to our five-step process meant for reduction inturbidity, with and without initial heating as explained in Table 20.4.

TABLE 20.1 PRODUCTION OF SLOP OILS USING HIGH SHEAR MIXING MACHINE SI.No. DESCRIPTION TEST 1 TEST 2 TEST 3 TEST 4 1 Name of Oil Used Free FreeCoconut Coconut Flowing Flowing Oil Oil ONGC Oil ONGC Oil 2 Total Massof Slop Oil (kg) 0.64 0.58 0.54 0.43 3 Mixing Time (min) 5 5 5 5 4 RPMof Mixing 10,000 10,000 10,000 10,000 5 Oil Content in Slop Oil (ppm) 3085 60 99 6 Time elapsed before checking 2.03 3.06 1.36 0.7 of Turbidity(min) 7 Average Turbidity of Slop 39 579 53 72 Oil (NTU)

TABLE 20.2 RESULTS OF VIGOROUS BOILING OF ABOVE SLOP OILS SI. No.DESCRIPTION TEST 1 TEST 2 TEST 3 TEST 4 1 Time for Boiling (min) 7 7 7 72 Temperature Range (° C.) 95-98 95-98 95-98 95-98 3 Average Turbidityof Slop 38.2 435 52.1 68.9 Oil after heating (NTU)

TABLE 20.3 PRODUCTION OF COCONUT OIL BASED SLOP OILS USING HIGH SHEARMIXING MACHINE Treatment Treatment Treatment SI. with with without No.DESCRIPTION Heating Boiling Heat 1 Total Mass of Slop Oil (Kg) 0.50 0.500.49 2 Mixing Time (min) 5.00 5.00 5.00 3 RPM of Mixing 10,000 10,00010,000 4 Oil content in Slop Oil (ppm) 2,499 2,499 2,499 5 Time elapsedbefore checking 4.00 3.70 4.05 of Turbidity (min) 6 Turbidity of SlopOil (NTU) 4,701 4,814 4,763

TABLE 20.4 STEP WISE RESULTS ON PROCESSING OF ABOVE SLOP OILS WITHOUTREMOVING THE EFFECT OF TIME Treatment Treatment Treatment SI. with withwithout No. DESCRIPTION Heating Boiling Heat Step 1: Heating of Slop Oil1 Time Span in minutes 126 5 — 2 Temperature range (° C.) 80-90 95-98 —3 Turbidity of Slop Oil after heating (NTU) 4,277 4,099 — Step 2:Centrifuging of Slop Oil at 4,500 RCF twice with NIL residence time atpeak RCF value 4 Turbidity of Slop Oil after 2nd Centrifuge (NTU) 553386 797 Step 3: Addition of Solvent, Centrifuging it once under sameconditions as above and then removal of entire top layer of Solvent +Oil 5 Name & Wt. % of Solvent added Toluene Toluene Toluene (7%) (7%)(7%) 6 Mode of Solvent Addition Vigorous Vigorous Vigorous hand handhand mixed mixed mixed 7 Turbidity of Slop Oil after removal of TopLayer 109 120 200 (NTU) Step 4: Removal of Solvent from Slop Oil throughBoiling with Free Water present therein 8 Turbidity of Slop Oil in NTUon cooling after 14.4 14.6 12.0 addition of make-up water that was lostthrough boiling Step 5: Addition of Alum with Residence Time in SettlingVessel 9 Wt. % Alum added to Slop Oil 0.05 0.05 0.05 10 Time permittedfor Flocculation of Oil and Solids 24.48 23.86 16.20 in Settling Vesselin Hours 11 Turbidity after Flocculation (NTU) 9.64 9.80 9.00 Step 6:Filtration 12 Turbidity of Filtrate after using 41 Grade — — 3.42Whatman filter paper (NTU) 13 Turbidity of filtrate after using 40 Grade0.37 0.30 0.78 Whatman filter paper (NTU) 14 Total time elapsed in hrssince preparation of 28 26 23.36 Slop Oil 15 Turbidity of Control Sampleof same Slop Oil 3,099 3,184 3,148 after same time since its preparation(NTU)

The study on effect of vigorous boiling on turbidity of slop oils asshown in tables 20.1 and 20.2 was found to be important because that waslimited to low turbidity, less ppm slop oils alone. This kind of slopoils were obtained after 2nd step of our 5-step process, i.e. aftercentrifuging for third time with solvent and then removing entiretopmost layer of solvent cum hydrocarbons.

Thereafter entire dispersed solvent from slop oils was boiled out withhelp from free water present therein. While so doing, we wanted toseparately evaluate the impact of boiling alone, apart from that ofsolvent removed, on residual turbidity of slop oils.

The study here showed that impact of boiling was small unless residualvalue of slop oils after boiling out solvent was high. The impact ofboiling was further reduced for residual values ranging from 38 to 69NTU and turbidity of slop oils by 2.09 to 4.5% of residual values.However, for high residual values like 435 NTU, reduction in turbidityon account of boiling alone was by 33% of residual turbidity value.Boiling related reduction in value was additional to that due to removalof solvent. The part of these reductions in turbidity values were onaccount of passage of time too. Accordingly it was concluded that impactof boiling can be neglected for low residual turbidity values.

As seen in table nos. 20.3 and 20.4, about 9 to 14% immediate reductionin turbidity values was observed with medium turbidity coconut oil basedslop oils due to heating without removing impact of passage of time.This impact was observed to be more with boiling. Effect of heating orboiling on turbidity values of coconut oil based slop oils progressivelyreduced with subsequent processing of slop oils. It was seen that theimpact of both heating and boiling was completely vanished after boilingout solvents or prior to adding of alum. Hence; it was ascertained thatprior heating or boiling of slop oils is not required.

Example-21 Time Adjusted Effect of Solvent Alone on Reducing Turbidityof Slop Oils

An impact of using low viscous solvent, like Toluene, alone on reductionin turbidity of slop oils after removing the impact of time fromreported turbidity results was studied.

Accordingly, 5 Wt. % Toluene was added to the prepared slop oils.Toluene was mixed in them using high shear mixer at 10,000 RPM for 1minute. Before addition of Solvent, Slop Oils were tested for turbidityand time was noted. Solvent added samples were allowed to stand for 20hours for most Oil and Solvent to collect at the top. Later, top layercontaining solvent and oil was separated from each Slop Oil Sample andremaining material was tested for turbidity after homogenization andagain the time was noted. Subsequently, entire residual solvent wasboiled out, in temperature range of 95° C. to 98° C. from remainingmaterial with help from free water present in sop oil. After cooling,make up water was added to replace the water lost through boiling.Thereafter, slop oils were again tested for turbidity and time wasnoted. Here each turbidity value of test sample was time-adjusted. Thiswas done with control samples where turbidity values continuouslychanged, often only reducing, with passage of time. After identicalelapsed time, turbidity values of control samples were added to those oftest samples that removed the impact of time from reported values, thusreflecting the impact of solvent alone.

TABLE 21.1 PRODUCTION OF ONGC BASED SLOP OILS USING HIGH SHEAR MACHINESI. NO. DESCRIPTION ONGC Free Flowing Oil 1 Total Mass of Slop Oils (kg)0.51 0.60 0.49 0.56 2 Time for mixing (min) 1 5 1 5 3 RPM used forproducing Slop 10,000 10,000 10,000 10,000 Oils 4 Oil content in SlopOils (ppm) 2,499 2,501 4,988 5,003 5 Time elapsed before checking 3.882.03 2.40 2.80 Turbidity (min) 6 Average Turbidity of Slop 5,6269,894 >10,000 >10,000 Oils (NTU)

TABLE 21.2 TIME ADJUSTED RESULTS ON ADDITION OF SOLVENT TO ABOVE SLOPOILS SI. NO. DESCRIPTION ONGC Free Flowing Oil 1 Name & Wt. % TolueneToluene Toluene Toluene Solvent added (5%) (5%) (5%) (5%) 2 Turbidity ofSlop Oils 5,626 9,894 >10,000 >10,000 before addition of Solvent (NTU) 3Turbidity of Slop Oils >10,000 >10,000 >10,000 >10,000 after addition ofSolvent (NTU) 4 Turbidity of Slop Oils 9,052 >10,000 >10,000 >10,000after removing residual Solvent through Boiling (NTU)

TABLE 21.3 PRODUCTION OF COCONUT OIL BASED SLOP OILS USING HIGH SHEARMACHINE SI. NO. DESCRIPTION Coconut Oil 1 Total Mass of Slop Oils (kg)0.53 0.56 0.51 0.54 2 Time of mixing (min) 1 5 1 5 3 RPM used forproducing Slop 10,000 10,000 10,000 10,000 Oils 4 Oil content in SlopOils (ppm) 2,498 2,501 5,003 4,951 5 Time elapsed before checking 3.122.70 1.96 1.72 Turbidity (min) 6 Average Turbidity of Slop 4,354 4,8567,816 8,886 Oils (NTU)

TABLE 21.4 PROCESSING OF ABOVE SLOP OIL BY USE OF SOLVENT SI. NO.DESCRIPTION Coconut Oil 1 Name & Wt. % Toluene Toluene Toluene TolueneSolvent added (5%) (5%) (5%) (5%) 2 Turbidity of Slop 4,354 4,856 7,8168,886 Oils before addition of Solvent (NTU) 3 Turbidity ofSlop >10,000 >10,000 >10,000 >10,000 Oils after addition of Solvent(NTU) 4 Turbidity of Slop 8,167 6,823 >10,000 >10,000 Oils after removalof Solvent through Azeotropic Boiling (NTU)

For slop oils produced from ONGC Free Flowing Oil, impact of mixing timerequired for their production was large compared to that for Coconut Oilbased slop oils. It was observed that the turbidity value went up from5,626 to 9,894 NTU for 2,500 ppm ONGC slop oil with increase in mixingtime from 1 to 5 minutes. Under same conditions, for Coconut Oil basedSlop Oils it rose from 4,354 to 4,856 NTU. For Slop Oils produced fromONGC Free Flowing Oil impact of increase in concentration ofhydrocarbons on turbidity value was also slightly larger than that forCoconut Oil based Slop Oils.

It was seen that addition of Toluene never helped, either with Coconutor with ONGC slop oils. It could not reduce turbidity of these slop oilsinspite of removing large amounts of hydrocarbons from slop oil andretaining them in the topmost layer along with it. On the contrary,after addition of solvent turbidity values infact went up inspite ofboiling entire solvent that was added. For 2,500 Slop Oils rise in valuewas lot more in case of 1 minutes mixed Slop Oils as compared to 5minutes mixed Slop Oils.

Solvent was invariably added into slop oils by mixing it for 1 minute at10,000 RPM. Probably this mixing might have further fragmented existingdroplets of Coconut Oil and ONGC Oil and that could have raisedturbidity values by increasing the population density of ultra-finedroplets. Impact of further fragmentation was expected to be higher incase of slop oils produced through 1 minute of mixing as compared tothose that had been generated after 5 minutes of mixing. Hence turbidityvalues of slop oils after 1 minute mixing we found to be increasing alot more. Probably use of solvent might have failed also because most ofthe solvent got consumed removing large oil droplets. Consequently,ultra fine droplets might have been remained intact with additional needof solvents in batches.

It was seen that with 5,000 ppm slop oils, the differential rise for 1and 5 minutes slop oils could not be established as final valuesexceeded our test equipment range. However, with 5,000 ppm Coconut Oilbased Slop Oils, at least their turbidity values went up with use ofsolvent even after boiling out the entire solvent that was added.

Example-22 Time Adjusted Effect of Centrifuge Alone on ReducingTurbidity of Slop Oils

Effect of centrifuge alone on reducing turbidity of slop oils afterremoving the impact of time from reported turbidity results was studied.Accordingly, the slop oils were prepared using Free Flowing ONGC Oil andalso Coconut Oil under parameters as explained in table nos. 22.1 and22.3. Table Nos. 22.2 and 22.4 showed time adjusted results of threerounds of centrifuge as well as the conditions under which samples werecentrifuged. After each round of centrifuge turbidity values were testedand time was noted only after carefully removing the entire top layer ofaccumulated oil. It was understood that meaning of time adjusted resultshave been explained under procedure explained in Example-21.

TABLE 22.1 PRODUCTION OF ONGC OIL BASED SLOP OIL USING HIGH SHEAR MIXINGMACHINE SI. NO. DESCRIPTION TEST 1 TEST 2 TEST 3 TEST 4 1 Total Mass ofSlop Oil (kg) 0.49 0.50 0.51 0.50 2 Mixing Time (min) 1 5 1 5 3 RPM ofMixing 10,000 10,000 10,000 10,000 4 Oil content in Slop Oil (ppm) 2,4962,486 5,001 4,993 5 Time elapsed before checking 3.02 3.35 4.10 4.10 ofTurbidity (min) 6 Average Turbidity of Slop5,911 >10,000 >10,000 >10,000 Oil (NTU)

TABLE 22.2 RESULTS OF CENTRIFUGING ABOVE ONGC OIL BASED SLOP OILS SI.No. DESCRIPTION TEST 1 TEST 2 TEST 3 TEST 4 Step: 1 Centrifuging of SlopOil at 4,500 RCF with NIL residence time at peak RCF value 1 Turbidityof Slop 5,911 >10,000 >10,000 >10,000 Oil before Centrifuge (NTU) 2Turbidity of Slop 1,302 2,382 2,307 4,682 Oil after 1st Centrifuge (NTU)3 Turbidity of Slop 891 1,746 1,518 3,976 Oil after 2nd Centrifuge (NTU)4 Turbidity of Slop 811 1,639 1,260 3,551 Oil after 3rd Centrifuge (NTU)

TABLE 22.3 PRODUCTION OF COCONUT OIL BASED SLOP OIL USING HIGH SHEARMIXING MACHINE SI. NO. DESCRIPTION TEST 1 TEST 2 TEST 3 TEST 4 1 TotalMass of Slop Oil (kg) 0.49 0.49 0.50 0.49 2 Mixing Time (min) 1 5 1 5 3RPM of Mixing 10,000 10,000 10,000 10,000 4 Oil content in Slop Oil(ppm) 2,496 2,499 4,975 4,990 5 Time elapsed before checking 4.10 4.301.09 11.96 of Turbidity (min) 6 Average Turbidity of Slop 4,408 4,8297,962 8,823 Oil (NTU)

TABLE 22.4 RESULTS OF CENTRIFUGING ABOVE COCONUT OIL BASED SLOP OILS SI.NO. DESCRIPTION TEST 1 TEST 2 TEST 3 TEST 4 Step: 1 Centrifuging of SlopOil at 4,500 RCF with NIL residence time at peak RCF value 1 Turbidityof Slop Oil before 4,408 4,829 7,962 8,823 Centrifuge (NTU) 2 Turbidityof Slop Oil after 856 1,080 2,109 3,347 1st Centrifuge (NTU) 3 Turbidityof Slop Oil after 433 625 1,933 2,694 2nd Centrifuge (NTU) 4 Turbidityof Slop Oil after 354 387 1,679 2,627 3rd Centrifuge (NTU)

It was seen that the turbidity values of slop oils prepared from FreeFlowing ONGC Oil was always higher than that of Coconut Oil based slopoils prepared under similar conditions. The turbidity of Coconut Oilbased Slop Oils increased both with mixing time employed for theirpreparation and also with concentration of hydrocarbons present whereinthe concentration of hydrocarbons present was having greater impact thanmixing time.

Time adjusted impact of centrifuge was found to be substantiallydependent on starting turbidity values. It progressively reducedturbidity with every successive operation. It was seen that impact offirst round of centrifuge was large. In successive rounds, the impactkept diminishing. It was observed that the centrifuge was lot moreeffective in removing large sized oil droplets since the impact of dragwas less on the droplets. It was seen that force of buoyancy workedbetter with large sized droplets with substantial reduction in turbidityin the first round. It was seen that the centrifuge became ineffectivedue to one or more of the following reasons. Firstly, centrifuge couldhave become ineffective once size variations of dispersed oil dropletsbecame narrow. Secondly, centrifuge could have

become ineffective once population density of dispersed droplets fallswith increasing mean free path. Thirdly, centrifuge could have becomeineffective as initial turbidity values were too large. Fourthly,centrifuge could have become ineffective due to dispersed oil dropletsthat might have electrically charged. Lastly, centrifuge could havebecome ineffective due to small density difference between oil andwater.

It was established that narrowing of variations in droplet size couldhave resulted in movement of all droplets with same velocity andacceleration. This could have resulted in fewer collisions and slowerrate of coalescence. Also, efficacy of centrifuge could have droppeddown with absence of sweeping effect of large sized oil droplets.Further, uniform size of dispersed droplets could have impaired thecentrifuge lot more than their small population density with large meanfree path. It was seen that with too high initial turbidity value orinitial population density of ultra-fine oil droplets, the centrifugeslowed down and that then impacted its efficacy. It was seen that,residual turbidity after 3^(rd) attempt at centrifuge was invariablylarge when initial turbidity values were high.

It was concluded that the centrifuge cannot reduce turbidity of slopoils to the required value of 1 to 4 NTU. In fact, the limitingturbidity values of the centrifuge were lot higher. This was more so incases of colored slop oils. It was further concluded that the densitydifference between oil and water and also the RCF and residence timeinside the centrifuge play significant role in this regard.

Example-23 Time-Solvent-Centrifuge Adjusted Combined Effect ofCentrifuge and Solvent Alone, on Reducing Turbidity of Slop Oils

Combined use of Solvent and Centrifuge on reducing Turbidity of SlopOils was studied after removing individual effects of time, centrifugeand also that of solvent, from all reported turbidity results.Accordingly, slop oils were prepared under conditions given in tablenos. 23.1 and 23.3. Subsequently, the turbidity values of slop oils weremeasured. Thereafter, these slop oils were centrifuged twice with nilresidence time at maximum RCF of 4,500. Further, the solvents were addedby mixing them into slop oils for 1 minute at 10,000 RPM. Thereafter,the contents were centrifuged once again with nil residence time atmaximum RCF of 4,500. Subsequently, residual solvent from slop oil wasboiled out in temperature range of 95° C. to 98° C. with help from freewater present in slop oils after entirely removing the top layer ofsolvent cum oil. After cooling, make up water was added that was lostthrough vigorous boiling. Then, the remaining material was tested forturbidity values and also the time was noted. To remove impact of time,we added to above results the amount by which turbidity values wouldhave reduced if we had retained them in vessels for same periods of timesince their production. Next to remove the impact of solvent alone, thetime adjusted amount by which turbidity values went up on addition ofsolvents into slop oils by mixing them in for 1 minute at 10,000 RPM wassubtracted. Finally, to remove the impact of centrifuge alone, we addedto above results the time adjusted amount by which turbidity values ofslop oils had got reduced after centrifuging them thrice with nilresidence at maximum RCF of 4,500.

TABLE 23.1 PRODUCTION OF ONGC OIL BASED SLOP OILS USING HIGH SHEARMIXING MACHINE SI. NO. DESCRIPTION TEST 1 TEST 2 TEST 3 TEST 4 1 TotalMass of Slop Oil (kg) 0.51 0.47 0.49 0.51 2 Mixing Time (min) 1 5 1 5 3RPM of Mixing 10,000 10,000 10,000 10,000 4 Oil content in Slop Oil(ppm) 2,498 2,498 4,999 5,006 5 Time elapsed before checking 1.85 2.123.10 3.56 of Turbidity (min) 6 Average Turbidity of Slop6,080 >10,000 >10,000 >10,000 Oil (NTU)

TABLE 23.2 PROCESSING OF ABOVE SLOP OILS BY COMBINING THE USE OF SOLVENTAND CENTRIFUGE SI. NO. DESCRIPTION TEST 1 TEST 2 TEST 3 TEST 4 1Turbidity of Slop Oils 6,080 >10,000 >10,000 >10,000 before addingSolvent & doing Centrifuge (NTU) 2 Name & Wt. % of Solvent TolueneToluene Toluene Toluene added (5%) (5%) (5%) (7%) 3 Turbidity of SlopOil after 3,572 — — — adding Solvent; doing centrifuge and then removingSolvent through Azeotropic Boiling (NTU)

TABLE 23.3 PRODUCTION OF COCONUT OIL BASED SLOP OILS USING HIGH SHEARMIXING MACHINE SI. NO. DESCRIPTION TEST 1 TEST 2 TEST 3 TEST 4 1 TotalMass of Slop Oil (kg) 0.52 0.50 0.50 0.51 2 Mixing Time (min) 1 5 1 5 3RPM of Mixing 10,000 10,000 10,000 10,000 4 Oil content in Slop Oil(ppm) 2,501 2,499 4,994 4,999 5 Time elapsed before checking 1.88 2.852.88 4.30 of Turbidity (min) 6 Average Turbidity of Slop 4,672 4,6537,332 8,685 Oil (NTU)

TABLE 23.4 PROCESSING OF ABOVE SLOP OILS BY COMBINING THE USE OF SOLVENTAND CENTRIFUGE SI. NO. DESCRIPTION TEST 1 TEST 2 TEST 3 TEST 4 1Turbidity of Slop Oils 4,672 4,653 7,332 8,685 before adding Solvent &doing Centrifuge (NTU) 2 Name & Wt. % of Solvent Toluene Toluene TolueneToluene added (5%) (5%) (5%) (7%) 3 Turbidity of Slop Oil after 1,1183,213 — — adding Solvent; doing centrifuge and then removing Solventthrough Azeotropic Boiling (NTU)

It was seen from test Nos. 2, 3 and 4 in table 23.2 and test Nos. 3 and4 in Table 23.4 that we could not get values because we could quantifythe impact of adding solvents to slop oils for these tests as can seenfrom table Nos. 21.2 & 21.4. However, without quantifying the impact ofusing solvents, we cannot remove the impact of solvent for these tests.

However, from test no. 1 for 2,500 ppm ONGC Oil based Slop Oil and fromtest no. 1 and 2 for 1 and 5 minutes mixed, 2,500 ppm Coconut Oil basedSlop Oils, it was found that these two unit operations reduced turbidityof slop oils only when combined. The table nos. 23.2 and 23.4 show thatthere was a synergetic effect in combining the use of Solvent with thatof centrifuge. Use of Solvent alone actually increased the turbidity ofSlop Oils by a large margin. Use of centrifuge by itself succeeded well,only when initial turbidity values were not large. But when solvent wascombined with centrifuge, it not only wiped out the entire negativeimpact of using solvent alone, but it additionally benefited in caseswhere initial turbidity values where large like ONGC slop oils.

It was ascertained that the centrifuge must preferentially be used forremoving large oil droplets while solvents must be used for removingultra fine droplets. Solvents must be added only after centrifuge hasceased to be effective for want of wide droplet size distribution or lowpopulation density of fine droplets or small density difference betweenoils and water. This combination was found must when initially turbidityof slop oils was large.

Example-24 Effect of Using Alum on Reducing Turbidity of Slop Oils

Impact of alum addition on reduction of turbidity of slop oils wasstudied. Accordingly, slop oil samples were prepared with both low andhigh turbidity values as per conditions mentioned in below mentionedtables 24.1A and 24.2A. Alum was added and settling time was provided asper figures mentioned in tables 24.1B and 24.2B. Alum was added in 3different proportions for high turbidity samples and turbidity valueswere evaluated over 4 days with and without adjusting the effect oftime.

Effect of Alum on Low Ppm Slop Oil—

TABLE 24.1A PRODUCTION OF SLOP OILS USING HIGH SHEAR MIXING MACHINE TEST1 TEST 2 TEST 3 TEST 4 TEST 5 SI. Name of Oil Used NO. DESCRIPTION ONGCFree Flowing Oil Coconut Oil 1 Total Mass of Slop Oil (kg) 0.45 0.460.59 0.57 0.48 2 Mixing Time (min) 5 5 5 5 5 3 RPM of Mixing 10,00010,000 10,000 10,000 10,000 4 Oil content in Slop Oil (ppm) 9 20 45 7 605 Time elapsed before checking of 5.4 4.2 4.2 6.6 3.6 Turbidity (min) 6Average Turbidity of Slop Oil (NTU) 7 19 60 8 56

TABLE 24.1B IMPACT OF ALUM ON ABOVE SLOP OILS SI. NO. DESCRIPTION TEST 1TEST 2 TEST 3 TEST 4 TEST 5 1 Turbidity of Slop Oil before 6.6 19 60 855 adding Alum (NTU) 2 Wt. % Alum added to Slop Oil 0.05 0.05 0.05 0.050.05 3 Time permitted for Settling 19.03 28.61 26.86 27.46 24 (Hrs) 4Turbidity Values after above 4.4 2.0 4.5 1.6 10.1 Settling Time (NTU) 5Wt. % reduction in Turbidity 33.33 89.47 92.50 80.00 81.64 of Slop Oilby adding Alum

Effect of Mum on High Ppm Slop Oil—

TABLE 24.2A PRODUCTION OF SLOP OILS USING HIGH SHEAR MIXING MACHINE SI.NO. DESCRIPTION TEST 1 TEST 2 TEST 3 Name of Oil Used ONGC CoconutCoconut Oil Oil Oil 1 Total Mass of Slop Oil (kg) 0.50 0.52 0.60 2Mixing Time (min) 3 5 5 3 RPM of Mixing 10,000 10,000 10,000 4 Oilcontent in Slop Oil (ppm) 2,495 2,438 499 5 Time elapsed before checking3.6 3.6 5.4 of Turbidity (min) 6 Average Turbidity of Slop 5,643 4,508484 Oil (NTU)

TABLE 24.2B IMPACT OF ALUM ON ABOVE SLOP OILS SI. NO. DESCRIPTIONS TEST1 TEST 2 TEST 3 1 Turbidity of Slop Oil before 4,755 4,675 484 addingAlum (NTU) 2 Wt. % of Alum added to Slop 0.05 0.05 0.05 Oil 3 Timepermitted for Settling 23.08 24.00 25.08 (Hrs) 4 Turbidity Valuesincluding the 45 18.7 8.6 Impact of Time (NTU) 5 Turbidity Valuesexcluding the 1702 1923 — Impact of Time (NTU) 6 Wt. % reduction inTurbidity 99.05 99.60 98.22 of Slop Oil by adding AlumEffect of Alum with Different Compositions on Slop Oil—

TABLE 24.3A PRODUCTION OF SLOP OILS USING HIGH SHEAR MIXING MACHINE SI.NO. DESCRIPTIONS TEST 1 TEST 2 Name of Oil Used ONGC Free CoconutFlowing Oil Oil 1 Total Mass of Slop Oil (kg) 0.49 0.50 2 Mixing Time(min) 5 5 3 RPM of Mixing 10,000 10,000 4 Oil content in Slop Oil (ppm)2,498 2,496 5 Time elapsed before checking 1.98 2.18 Turbidity (min) 6Average Turbidity of Slop >10,000 4,740 Oil (NTU)

TABLE 24.3B ADDITION OF ALUM WITH DIFFERENT PROPORTIONS TO SLOP OIL SI.NO. DESCRIPTIONS TEST 1 TEST 2 Step-1: Addition of Alum with ResidenceTime in Settling Vessel 1 Turbidity of Slop Oil before addingAlum >10,000 4,740 (NTU) 2 Wt. % Alum added to Slop Oil 0.05 0.10 0.150.05 0.10 0.15 Day-1 3 Time permitted for Settling (hrs) 24.05 24.1424.13 24.02 24.55 24.50 4 Turbidity Values including the impact of 4,1655.44 5.38 9.52 3.59 3.54 time (NTU) 5 Turbidity Values excluding theimpact of 4,364 204 204 194 188 188 time (NTU) Day-2 6 Time permittedfor Settling (Hrs) 48.06 47.96 47.95 47.95 47.96 47.97 7 TurbidityValues including the impact of 2,468 5.36 3.9 2.53 6.27 2.67 time (NTU)8 Turbidity Values excluding the impact of 2,634 171 170 105 108 105time (NTU) Day-3 9 Time permitted for Settling (Hrs) 71.52 71.36 71.3471.46 71.33 71.28 10 Turbidity Values including the impact of 366 5 2.614.72 4.79 3.31 time (NTU) 11 Turbidity Values excluding the impact of691 330 328 16 16 15 time (NTU) Day-4 12 Time for Settling (Hrs) 96.1796.14 96.11 96.49 95.87 96.34 13 Turbidity Values after including impactof 10.6 2.3 1.14 3.49 2.19 2.26 time (NTU) 14 Turbidity Values afterexcluding the impact 171 162 161 35 34 34 of time (NTU)

It was observed that impact of Alum on reducing turbidity of slop oilsin 24 hours was more when initial turbidity values were large. As seenin table 24.2B, on removing the impact of time, one can see that Impactof Alum alone on reduction of turbidity values of slop oils was about1.5 times more than that of time itself.

As seen from table 24.3B, addition of 0.05 wt. % alum is not adequatewhen initial turbidity values are more than 10,000 NTU. Addition of Alummust be increased to 0.1 wt. %. However, beyond addition of 0.1 wt. %alum there was no further improvement seen. Hence, it was ascertainedthat amount of Alum added was important only when one was interested toget quick results in a day or two. Combined impact of alum and time wasmore than adequate to reduce turbidity values from greater than 10,000NTU to about 5.5 NTU if given 24 hours. However, then removal of the oillayer contaminated with Alum from water was found rather difficult.Besides, calorific value of oil was reduced by 2% as shown below inExample-29. Also, it was observed that alkali content of oil went upwith contamination from Alum. It was also observed that viscosity of oildramatically changes per wt. % of Alum present therein.

Example-25 Effect of Combined Use of Alum, Heat and Time on ReducingTurbidity of Slop Oils

It was an aim to evaluate the impact of combined use of Alum, heat andtime on reducing turbidity of slop oils and comparing that, with justthe use of alum with time alone. Accordingly, low turbidity slop oilsamples were prepared as per conditions mentioned in table-25.1.Thereafter, Alum was added and kept part of samples at ambientconditions and their initial and final turbidity values were tested overvarying time from 3 hours to 5.8 hours. The remaining part of sampleswere heated in oven at 80° C. over varying time from 1 to 4 hours andeven these were tested for initial and final turbidity values.Subsequently, make up water was added for heated samples to replenishevaporated water.

TABLE 25.1 PRODUCTION OF SLOP OILS USING HIGH SHEAR MIXING MACHINE SI.No. DESCRIPTION TEST 1 TEST 2 TEST 3 TEST 4 Name of Oil Used ONGC FreeCoconut Flowing Oil Oil 1 Total Mass of Slop Oil (kg) 0.57 0.54 0.630.56 2 Mixing Time (min) 5 5 5 5 3 RPM of Mixing 10,000 10,000 10,00010,000 4 Oil content in Slop Oil (ppm) 30 60 60 99 5 Time elapsed beforechecking 4.00 4.12 2.36 1.82 Turbidity (min) 6 Average Turbidity of Slop42.1 90.6 56.1 66.5 Oil (NTU)

TABLE 25.2 ADDING ALUM AND HEATING OF ABOVE SLOP OILS SI. NO.DESCRIPTION TEST 1 TEST 2 TEST 3 TEST 4 Step-1: Addition of Alum withResidence time in Settling Vessel 1 Turbidity of Slop Oil before addingAlum 42.1 90.6 56.1 66.5 (NTU) 2 Wt % of Alum added to Slop Oil 0.050.05 0.05 0.05 3 Time permitted for Flocculation of Oil & 5.04 5.84 3.444.56 Solids in Settling Vessel (Hrs) 4 Turbidity after Flocculation(NTU) 11.4 92.7 75.9 72.9 Step-2: Heating of Alum added Slop Oil 1 Timekept for heating (Hrs) 4 4 1 3 2 Set Temperature of instrument (° C.) 8080 80 80 3 Average Turbidity of Alum added Slop Oil 2.92 19.1 18.5 10.8after heating (NTU) 4 Time taken for the process of heating alum 5.115.72 3.22 4.43 added Slop oil (Hrs)

As can be seen from table 25.2, the combined impact of alum, heat andtime was found to be far better than that of just alum and time alone,on reduction of turbidity values of low turbidity ONGC and Coconut Oilbased Slop Oils. In Test-1, it was observed that turbidity value felldown by 73% in 5.04 hours in case on non-heating of Alum added slop oil.However, Alum added slop oil when heated at 80° C. for 4 hours, theturbidity of the slop oil fell down by 93% in 5.11 hours. In tests 2, 3and 4 when not heated turbidity values were in fact found to beincreased by 2.3%, 35.3% and 9.6% in 5.84, 3.44 and 4.56 hoursrespectively. The turbidity values of slop oils actually went up evenmore than their initial values with time when Alum added slop oil wasnot heated with lower initial turbidity and lesser settling time.

However, the turbidity value fell down by 67% instead in case where Alumadded slop oil sample when heated at 80° C. even with low initialturbidity value of 56.1 NTU and even with less time of 1 hour. Also,with initial turbidity value of 42.1 NTU and with 4 hours of heating at80° C. the fall was 93% in 5.11 hours. It ascertained that more thelength of time over which samples were heated faster was the fall inturbidity values. This experiment established the fact that treatmentwith Alum could be speeded up to reduce our overall processing time ifneeded by applying low intensity heat.

Example-26 Effect of Filtration on Reducing Turbidity of Slop Oils

In order to evaluate impacts of fast and slow filtration rates onreduction of turbidity values of high and low initial turbidity slopoils, the slop oil samples were prepared as per conditions mentioned intable 26.1. These samples were filtered repeatedly four times using 40and 41 Grade Whatman cellulose Filter Papers. In one set of readings thesame filter paper was repeatedly used while in the other set of readingsnew filter papers were used each time. The turbidity values were notedbefore and after each filtration. The time taken for filtration of agiven weight of slop oil was also noted each time to arrive at the rateof filtration.

TABLE 26.1 PRODUCTION OF SLOP OILS USING HIGH SHEAR MIXING MACHINE SI.No. DESCRIPTION TEST 1 TEST 2 Name of Oil Used ONGC Free Coconut FlowingOil Oil 1 Total Mass of Slop Oil (kg) 0.49 0.51 2 Mixing Time (min) 5 53 RPM of Mixing 10,000 10,000 4 Oil content in Slop Oil (ppm) 2,4802,497 5 Time elapsed before checking 4.70 3.72 Turbidity (min) 6 AverageTurbidity of Slop 9,356 4,434 Oil (NTU)

TABLE 26.2 FILTRATION PROCESS USING WHATMAN FILTER PAPERS FOR ABOVE SLOPOILS DESCRIPTION SI. Step-1: Filtration using NO. Whatman Filter paperTEST 1 TEST 2 1 Mode of using Filter Paper Same Filter Each Time SameFilter Each Time Paper used New Filter Paper used New Filter each timePaper used each time Paper used 2 Grade of Whatman Filter 40 41 40 41 4041 40 41 Paper used 3 Turbidity: After 1st 1,971 6,007 2,063 6,543 3,8884,596 3,918 4,689 Filtration (NTU) 4 Flow Rate of Slop Oil 2.07 13.952.4 7.78 7.48 45.43 6.73 91.31 collected for 1st Filtration (g/min) 5Turbidity: After 2nd 1,096 3,033 1,147 4,370 3,646 4,650 3,373 4,666Filtration (NTU) 6 Flow Rate of Slop Oil 0.62 2.9 6.95 46.33 7.46 54.136.4 82.1 collected for 2nd Filtration (g/min) 7 Turbidity: After 3rd 7301,960 764 4,486 3,292 4,629 2,877 4,489 Filtration (NTU) 8 Flow Rate ofSlop Oil 0.73 1.83 5.31 27.66 5.38 33.29 3.18 72.44 collected for 3rdFiltration (g/min) 9 Turbidity: After 4th 539 1,021 564 4,224 2,9064,670 2,476 4,428 Filtration (NTU) 10 Flow Rate of Slop Oil 0.66 1.535.46 64.19 3.81 22.65 8.68 89.06 collected for 4th Filtration (g/min) 11Total time elapsed since 3.26 2.15 preparation of Slop Oil (hrs) 12Turbidity of Control Sample 9,857 4,438 of same Slop Oil after same timesince its preparation (NTU)

It was seen that 40 Grade Whatman filter paper having 8 micron pore sizegave much lower turbidity values after each filtration however found tobe slow while filtering. It was even slower when the same paper wasrepeatedly used each time. It was also found to be far slower in case ofhigh turbidity slop oils. It was observed that the process slowed downbut the quality of filtrate was improved with repeated use of samefilter paper in order to get lower turbidity values. It was seen thatfiltration failed to give consistent results each time. The rate offiltration changed each time and reduction in turbidity values alsochanged accordingly. It was seen that efficacy of filtration wasdependent on the nature of hydrocarbon in the slop oil. For instance, ascan be seen from Table 26.2 that filtration was lot less effective forCoconut Oil based slop oils than ONGC Oil based slop oils.

However, it was seen that other than as finishing step for reduction oflast bits of turbidity values it was found to be a desirable industrialprocess because of one or more of the following reasons. Firstly, thefiltration process was found to be very slow process. Secondly, thefiltration process was found to be an inconsistent process. Thirdly, thefiltration medium was found to be blocked fast when pore size was smallthereby making further process even slower. Fourthly, the hydrocarbonpresent in slop oil cannot be recovered easily or in saleable form.Lastly, presence of solids in slop oils further impaired this process interms of its efficacy and flow rates.

Example-27 Effect of Combining Uses of Alum and Filtration on Reductionof Turbidity of Slop Oils

In order to evaluate impact of combined use of both Alum and filtrationon reduction of turbidity of slop oils having both low and mediumturbidity values, slop oil samples were prepared under conditionsmentioned in below tables 27.1A and 27.2A. Alum was added to thesesamples after testing for initial turbidity values 0.05 wt. %. Theturbidity values of these samples were tested again after close to 24hours. Further, the samples were successively filtered with Grade 41 andthen with Grade 40 Whatman Cellulose Filter Papers and after eachfiltration reduction in turbidity values were recorded.

Effect of Alum and Filtration on Turbidity of Low ppm Slop Oils—

TABLE 27.1A PRODUCTION OF SLOP OILS USING HIGH SHEAR MIXING MACHINE TEST1 TEST 2 TEST 3 TEST 4 TEST 5 SI. Name of Oil Used NO. DESCRIPTION ONGCFree Flowing Oil Coconut Oil 1 Total Mass of Slop Oil (kg) 0.45 0.460.59 0.57 0.48 2 RPM of Mixing 10,000 10,000 10,000 10,000 10,000 3Mixing Time (min) 5 5 5 5 5 4 Oil content in Slop Oil (ppm) 9 20 45 7 605 Time elapsed before checking 0.09 0.07 0.07 0.11 0.06 Turbidity (min)6 Average Turbidity of Slop Oil 7 19 60 8 56 (NTU)

TABLE 27.1B PROCESSING OF ABOVE SLOP OILS BY ADDITION OF ALUM AND THENFILTRATION WITH WHATMAN CELLULOSE FILTER PAPERS. SI. ONGC Free NO.DESCRIPTION Flowing Oil Coconut Oil 1 Turbidity of Slop Oils before 6.619 60 8 55 adding Alum (NTU) 2 Wt. % of Alum added to Slop 0.05 0.050.05 0.05 0.05 Oils 3 Time permitted for Settling 19.03 28.61 26.8627.46 24.00 (Hrs) 4 Turbidity after above Settling 4.4 2.0 4.5 1.6 10.1Time (NTU) 5 % Reduction in Turbidity of 33.33 89.47 92.50 80.00 81.64Slop Oils by adding Alum 6 Turbidity of Filtrate after 1.8 1.3 5.2 0.943.8 using 41 Grade Whatman Filter Paper (NTU) 7 Turbidity of Filtrateafter 0.68 0.75 1.9 0.53 0.19 using 40 Grade Whatman Filter Paper (NTU)

Effect of Alum and Filtration on Turbidity of High ppm Slop Oils—

TABLE 27.2A PRODUCTION OF SLOP OILS USING HIGH SHEAR MIXING MACHINE SI.NO. DESCRIPTION TEST 1 TEST 2 TEST 3 Name of Oil Used ONGC CoconutCoconut Free Oil Oil Flowing Oil 1 Total Mass of Slop Oil (kg) 0.50 0.520.60 2 Mixing Time (min) 10,000 10,000 10,000 3 RPM of Mixing 3 5 5 4Oil content in Slop Oil (ppm) 2,495 2,438 499 5 Time elapsed beforechecking 0.06 0.06 0.09 Turbidity (min) 6 Average Turbidity of Slop5,643 4,508 484 Oil (NTU)

TABLE 27.2B PROCESSING OF ABOVE SLOP OILS BY ADDITION OF ALUM AND THENFILTRATION WITH WHATMAN CELLULOSE FILTER PAPERS SI. NO. DESCRIPTION TEST1 TEST 2 TEST 3 1 Turbidity of Slop Oils before 4,755 4,675 484 addingAlum (NTU) 2 Wt. % Alum added to Slop Oils 0.05 0.05 0.05 3 Timepermitted for Settling 23.08 24.00 25.08 (Hrs) 4 Turbidity Valueswithout 45 18.7 8.6 adjusting impact of Time (NTU) 5 Turbidity Valuesafter 1,702 1,923 — adjusting impact of Time (NTU) 6 % Reduction inTurbidity of 99.05 99.60 98.22 Slop Oils by adding Alum 7 Turbidity ofFiltrate after using 16.7 9.4 2.33 41 Grade Whatman Filter Paper (NTU) 8Turbidity of Filtrate after using 0.58 0.77 1.05 40 Grade Whatman FilterPaper (NTU)

It was observed that percentage impact of Alum was lot more, in sametime span and with same dosage, for slop oils with large initialturbidity values as can be seen by comparing table nos. 27.1B and 27.2B.It was further seen that Alum could make use of centrifuge and solventredundant. But it was hold untrue. This was because Alum took the sametime and dosage to reduce turbidity of slop oil from 4,755 to 45 NTU asmuch as it took to reduce it from 45 to 4.5 NTU. Alum was needed toreduce turbidity up to 2-5 NTU. Therefore, it was ascertained thatstarting turbidity for Alum must be below 60 to 70 NTU. Once turbidityvalues were brought down from 2-5 NTU then even fast filtration wasobserved to be very effective for delivering water with around 1 NTU andalso the load on or blocking of filtering media was observed to besmall. Secondly, Alum was found to be adversely affecting the quality ofoil collected from slop oils. Accordingly, it was ascertained that ifquality of oil collected is not important and if time taken forfiltration and saturation of filtering media can be ignored, then alumcum filtration can make the use of centrifuge and solvent redundantly asfar as processing of slop oils is concerned.

Example-28 Overall Effect of Combining the Use of Centrifuge, Solvent,Alum & Filtration with Varying Solvents on Reducing Turbidity of VariousSlop Oils

It was an aim to evaluate combined effect of centrifuge, solvent, alumand filtration and also the effect of various solvents on reducingturbidity of slop oils prepared from various oils/hydrocarbons.Accordingly, slop oils were prepared as per conditions mentioned intable nos. 28.1A, 28.2A, 28.3A, 28.4A, 28.5A, 28.6A and 28-7A.Procedures of preparation were also mentioned in table nos. 28.1B,28.2B, 28.3B, 28.4B, 28.5B, 28.6B and 28.7B. Subsequently, solvents likeToluene and Xylene were used mixed in different proportions. Thesolvents were mixed with the slop oils using high shear mixer at 8,090RPM for 1 minute. The oil content in slop oils was varied from 5 PPM to4, 99,052 PPM. The various oils used were selected from one or more ofthe following Coconut Oil, Furnace Oil, Diesel, ONGC Free Flowing Oiland ONGC viscous hydrocarbons. Subsequently, all four processing stepsinvolving the use of Centrifuge, Solvent, Alum and Filtration wereemployed in sequential manner. Accordingly, following observations weremade.

Coconut Oil Based Slop Oils—

TABLE 28.1A PRODUCTION OF COCONUT OIL BASED SLOP OILS USING HIGH SHEARMIXING MACHINE SI. No. DESCRIPTION TEST 1 TEST 2 TEST 3 TEST 4 1 TotalMass of Slop Oils (kg) 0.52 0.66 0.51 0.51 2 Mixing Time (min) 5 5 5 5 3RPM of Mixing 10,000 10,000 10,000 10,000 4 Oil content in Slop Oil(ppm) 5 80 4,996 4,999 5 Time elapsed before checking 4.10 12.76 5.554.30 of Turbidity (min) 6 Average Turbidity of Slop 22 65 9,070 8,685Oils (NTU)

TABLE 28.1B PROCESSING OF ABOVE SLOP OILS BY COMBINING THE USE OFCENTRIFUGE, SOLVENT, ALUM AND FILTRATION SI. No. DESCRIPTION TEST 1 TEST2 TEST 3 TEST 4 Step 1: Centrifuging of Slop Oils at 4,500 RCF twicewith NIL Residence time at peak RCF value 1 Average Turbidity of SlopOils after 2nd 16 24 2,354 2,358 Centrifuge (NTU) Step 2: Addition ofSolvent & then Centrifuging it once again under same conditions as aboveand then removal of entire top layer of Solvent + Oil 2 Name & Wt. % ofSolvent added Xylene Xylene Xylene Toluene (5%) (5%) (7.2%) (7%) 3 Modeof Solvent Addition High High High High shear shear shear shear mixingmixing mixing mixing 4 Time of Mixing (min) 1 minute 1 minute 1 minute 1minute 5 RPM used for mixing Solvent 8,090 8,090 8,090 8,090 6 AverageTurbidity of Slop Oils after 29 62 421 395 removal of top layer (NTU)Step 3: Removal of Solvent from Slop Oils through Boiling with FreeWater present therein 7 Average Turbidity of Slop Oils in 6 12 42 54 NTUon cooling after addition of make-up water that was lost through boilingStep 4: Addition of Alum with Residence Time in Settling Vessel 8 Wt. %of Alum added to Slop Oil 0.05 0.05 0.05 0.05 9 Time permitted forSettling (hrs) 25.31 25.48 23.15 23.26 10 Average Turbidity after aboveSettling 0.743 0.602 1.38 5.01 Time (NTU) Step 6: Filtration 11 AverageTurbidity of Filtrate after using 0.647 0.601 1.27 3.26 41 Grade WhatmanFilter Paper (NTU) 12 Average Turbidity of Filtrate after using 0.4520.554 0.34 1.04 40 Grade Whatman Filter Paper (NTU) 13 Total timeelapsed since preparation of 27.31 27.48 25.15 25.26 Slop Oils (hrs)

TABLE 28.2A PRODUCTION OF COCONUT OIL BASED SLOP OILS USING HIGH SHEARMIXING MACHINE SI. No. DESCRIPTION TEST 1 TEST 2 TEST 3 TEST 4 TEST 5 1Total Mass of Slop 0.51 0.51 0.50 0.50 0.50 Oils (kg) 2 Mixing Time(min) 5 5 5 5 5 3 RPM of Mixing 10,000 10,000 10,000 10,000 10,000 4 Oilcontent in Slop 9,976 9,967 100,069 250,079 499,052 Oil (ppm) 5 Timeelapsed before 3.03 4.66 4.80 6.18 5.30 checking of Turbidity (min) 6Average Turbidity of >10000 >10000 7,977 8,498 >10,000 Slop Oils (NTU)

TABLE 28.2B PROCESSING OF ABOVE SLOP OIL BY COMBINING THE USE OFCENTRIFUGE WITH SOLVENT, ALUM AND THEN FILTRATION SI. No. DESCRIPTIONTEST 1 TEST 2 TEST 3 TEST 4 TEST 5 Step 1: Centrifuging of Slop Oil at4,500 RCF twice with NIL Residence time at peak RCF value 1 AverageTurbidity of 3,494 3,499 >10,000 >10,000 1,554 Slop Oil after 2ndCentrifuge (NTU) Step 2: Addition of Solvent & then Centrifuging it onceunder same conditions as above and then removal of entire top layer ofSolvent + Oil 2 Name & Wt. % Solvent Toluene Xylene Xylene Xylene Xyleneadded (7%) (7%) (22%) (17%) (20%) 3 Mode of Solvent High High High HighHigh addition shear shear shear shear shear mixing mixing mixing mixingmixing 4 Time of mixing (min) 1 minute 1 minute 1 minute 1 minute 1minute 5 Maximum RPM used for 8,090 8,090 8,090 8,090 8,090 mixingSolvent 6 Average Turbidity of 450 2,216 556 245 566 Slop Oil afterremoval of top layer (NTU) Step 3: Removal of Solvent from Slop Oilthrough boiling with free water present therein 7 Average Turbidity of39 103 48 15 56 Slop Oil in NTU on cooling after addition of make-upwater that was lost through boiling Step 5: Addition of Alum withResidence Time in Settling Vessel 8 Wt. % Alum added to 0.05 0.05 0.050.05 0.05 Slop Oil 9 Time permitted for 22.14 22.30 22.86 22.50 19.18Settling (hrs) 10 Average Turbidity after 1.59 9.84 14.4 2.02 52.2 aboveSettling Time (NTU) Step 6: Filtration 11 Average Turbidity of 1.34 5.6810.6 1.36 43.7 Filtrate after using 41 Grade Whatman Filter paper (NTU)12 Average Turbidity of 0.83 1.26 2.21 1.32 9.61 Filtrate after using 40Grade Whatman Filter paper (NTU) 13 Total time elapsed since 24.14 24.3027.86 27.93 24.54 preparation of Slop Oil (hrs)

Furnace Oil Based Slop Oils—

TABLE 28.3A PRODUCTION OF FURNACE OIL BASED SLOP OILS USING HIGH SHEARMIXING MACHINE SI. No. DESCRIPTION TEST 1 TEST 2 TEST 3 1 Total Mass ofSlop Oils (kg) 0.49 0.49 0.49 2 Mixing Time (min) 5 5 5 3 RPM of Mixing10,000 10,000 10,000 4 Oil content in Slop Oil (ppm) 1,346 1,132 2,498 5Time elapsed before checking 4.20 6.52 5.35 of Turbidity (min) 6 AverageTurbidity of Slop 3,370 2,959 6,742 Oils (NTU)

TABLE 28.3B PROCESSING OF ABOVE SLOP OIL BY COMBINING THE USE OFCENTRIFUGE WITH SOLVENT, ALUM AND THEN FILTRATION SI. No. DESCRIPTIONTEST 1 TEST 2 TEST 3 Step 1: Centrifuging of Slop Oil at 4,500 RCF twicewith NIL Residence time at peak RCF value 1 Average Turbidity of SlopOil after 2nd 2,225 1,065 1,961 Centrifuge (NTU) Step 2: Addition ofSolvent & then Centrifuging it once under same conditions as above andthen removal of entire top layer of Solvent + Oil 2 Name & Wt. % Solventadded Xylene Xylene Xylene (5%) (5%) (5%) 3 Mode of Solvent additionHigh High High shear shear shear mixing mixing mixing 4 Time of mixing(min) 1 minute 1 minute 1 minute 5 RPM used for mixing Solvent 8,0908,090 8,090 6 Average Turbidity of Slop Oil after 161 20 69 removal oftop layer (NTU) Step 3: Removal of Solvent from Slop Oil through Boilingwith free water present therein 7 Average Turbidity of Slop Oil on 38 1239 cooling after addition of make-up water that was lost through boiling(NTU) Step 4: Addition of Alum with Residence Time in Settling vessel 8Wt. % Alum added to Slop Oil 0.05 0.05 0.05 9 Time permitted forSettling Vessel (hrs) 18.60 18.30 18.23 10 Average Turbidity after aboveSettling 1.81 0.672 1.34 Time (NTU) Step 5: Filtration 11 AverageTurbidity of Filtrate after using 1.28 0.417 1.15 41 Grade WhatmanFilter paper (NTU) 12 Average Turbidity of Filtrate after using 0.9380.254 1.11 40 Grade Whatman Filter paper (NTU) 13 Total time elapsedsince preparation of 22.58 22.36 23.40 Slop Oil (hrs)

Diesel Based Slop Oils—

TABLE 28.4A PRODUCTION OF DIESEL BASED SLOP OILS USING HIGH SHEAR MIXINGMACHINE SI. No. DESCRIPTION TEST 1 TEST 2 TEST 3 1 Total Mass of SlopOils (kg) 0.51 0.49 0.52 2 Mixing Time (min) 13.53 13.42 13.48 3 RPM ofMixing 8,090 8,030 8,130 4 Oil content in Slop Oil (ppm) 2,492 2,4997,442 5 Time elapsed before checking 5.47 3.45 3.57 of Turbidity (min) 6Average Turbidity of Slop 3,442 3,852 9,702 Oils (NTU)

TABLE 28.4B PROCESSING OF SLOP OIL FROM TABLE 28.4A BY COMBINING THE USEOF CENTRIFUGE WITH SOLVENT, ALUM AND THEN FILTRATION SI. No. DESCRIPTIONTEST 1 TEST 2 TEST 3 Step 1: Centrifuging of Slop Oil at 4,500 RCF twicewith NIL Residence time at peak RCF value 1 Average Turbidity of SlopOil after 2nd 37 28 67 Centrifuge (NTU) Step 2: Addition of Solvent &then Centrifuging it once under same conditions as above and thenremoval of entire top layer of Solvent + Oil 2 Name & Wt. % Solventadded Toluene Xylene Toluene (2%) (2%) (2%) 3 Mode of Solvent additionVigorous Vigorous Vigorous hand hand hand mix mix mix 4 Time of mixing(min) — — — 5 Maximum RPM used for mixing Solvent — — — 6 AverageTurbidity of Slop Oil after 35 46 77 removal of top layer(NTU) Step 3:Removal of top layer Solvent + Oil 7 Wt. % of Diesel + Solvent recovered97.78 97.34 97.12 8 Moisture in above as per BTX (ppm) 312 284 322 Step4: Removal of Solvent from Slop Oil through boiling with free waterpresent therein 9 Average Turbidity of Slop Oil in NTU 14 10 31 oncooling after addition of make-up water that was lost through boilingStep 5: Addition of Alum with Residence Time in Settling vessel 10 Wt. %Alum added to Slop Oil 0.05 0.05 0.05 11 Time permitted for Settling(hrs) 18.12 17.54 18.31 12 Average Turbidity after above Settling 1.180.356 1.39 Time (NTU) Step 6: Filtration 13 Average Turbidity ofFiltrate after using 1.07 0.352 0.79 41 Grade Whatman Filter paper (NTU)14 Average Turbidity of Filtrate after using 0.49 0.249 0.68 40 GradeWhatman Filter paper (NTU) 15 Total time elapsed since preparation of25.48 24.3 25.40 Slop Oil (hrs) 16 Average Turbidity of Control Sampleof 277 330 — same Slop Oil after same time since its preparation (NTU)

ONGC Free Flowing Oil Based Slop Oils—

TABLE 28.5A PRODUCTION OF ONGC OIL BASED SLOP OILS USING HIGH SHEARMIXING MACHINE SI. No. DESCRIPTION TEST 1 TEST 2 TEST 3 TEST 4 TEST 5TEST 6 1 Total Mass of 0.52 0.48 0.51 0.49 0.50 0.51 Slop Oils (kg) 2Mixing Time 5 5 5 5 5 5 (min) 3 RPM of Mixing 10,000 10,000 10,00010,000 10,000 10,000 4 Oil content in Slop 500 500 1,482 1,489 4,9995,006 Oil (ppm) 5 Time elapsed 4.3 3.26 4.11 3.19 4.17 3.34 beforechecking of Turbidity (min) 6 Average Turbidity 1,511 1,567 4,8595,149 >10,000 >10,000 of Slop Oils (NTU)

TABLE 28.5B PROCESSING OF ABOVE SLOP OIL BY COMBINING THE USE OFCENTRIFUGE WITH SOLVENT, ALUM AND THEN FILTRATION SI. No. DESCRIPTIONTEST 1 TEST 2 TEST 3 TEST 4 TEST 5 TEST 6 Step 1: Centrifuging of SlopOil at 4,500 RCF twice with NIL Residence time at peak RCF value 1Average Turbidity 686 645 1,783 1,792 4,364 4,427 of Slop Oil after 2ndCentrifuge (NTU) Step 2: Addition of Solvent & then Centrifuging it onceunder same conditions as above and then removal of entire top layer ofSolvent + Oil 2 Name & Wt. % Toluene Xylene Toluene Xylene XyleneToluene Solvent added (5%) (5%) (7%) (7%) (7%) (7%) 3 Mode of SolventHigh High High High High High addition shear shear shear shear shearshear mixing mixing mixing mixing mixing mixing 4 Time of mixing 1minute 1 minute 1 minute 1 minute 1 minute 1 minute (min) 5 Maximum RPM8,090 8,090 8,090 8,090 8,090 8,090 used for mixing Solvent 6 AverageTurbidity 2,512 824 615 1,564 2,115 1,930 of Slop Oil after removal oftop layer (NTU) Step 3: Removal of Solvent from Slop Oil through boilingwith free water present therein 7 Average Turbidity 59 33 34 41 72 89 ofSlop Oil on cooling after addition of make- up water that was lostthrough boiling Step 4: Addition of Alum with Residence Time in SettlingVessel 8 Wt. % Alum added 0.05 0.05 0.05 0.05 0.05 0.05 to Slop Oil 9Time permitted for 24.10 24.20 23.40 24.60 24.40 23.48 Settling (hrs) 10Average Turbidity 20.9 11 2.63 7.89 5.83 2.84 after above Settling Time(NTU) Step 5: Filtration 11 Average Turbidity 3.83 — 2.35 3.55 3.07 1.64of Filtrate after using 41 Grade Whatman Filter paper (NTU) 12 AverageTurbidity 1.2 1.71 0.81 1.26 1.04 1.14 of Filtrate after using 40 GradeWhatman Filter paper (NTU) 13 Total time elapsed 26.10 26.2 25.45 26.626.4 25.48 since preparation of Slop Oil (hrs) 14 Average Turbidity — —— — 3,683 3,701 of Control Sample of same Slop Oil after same time sinceits preparation (NTU)

TABLE 28.6A PRODUCTION OF ONGC OIL BASED SLOP OILS USING HIGH SHEARMIXING MACHINE SI. No. DESCRIPTION TEST 1 TEST 2 TEST 3 TEST 4 1 TotalMass of Slop Oils (kg) 0.49 0.49 0.51 0.5 2 Mixing Time (min) 1 5 5 5 3RPM of Mixing 10,000 10,000 10,000 10,000 4 Oil content in Slop Oil(ppm) 2,498 2,498 9,997 47,618 5 Time elapsed before checking 3.54 4.104.20 5.43 of Turbidity (min) 6 Average Turbidity of Slop 4,6306,119 >10,000 >10,000 Oils (NTU)

TABLE 28.6B PROCESSING OF SLOP OIL FROM TABLE 28.6A BY COMBINING THE USEOF CENTRIFUGE WITH SOLVENT, ALUM AND THEN FILTRATION SI. NO. DESCRIPTIONTEST 1 TEST 2 TEST 3 TEST 4 Step 1: Centrifuging of Slop Oil at 4,500RCF multiple times with NIL Residence time at peak RCF value 1 Name &Wt. % Solvent Toluene Toluene Toluene Toluene added (18%) (18%) (85%)(310%) 2 Mode of Solvent Vigorous Vigorous Mild Vigorous Mild Vigorousaddition hand hand mix hand hand hand hand mix mix mix mix mix 3 AverageTurbidity of 1,570 2,170 108 139 2,300 710 Slop Oil after removal of toplayer (NTU) Step 2: Removal of top layer Solvent + Oil 4 Wt. % ONGCOil + 95.64% 92.95% 93.79% 95.68% Solvent recovered 5 Moisture in aboveas 9,246 3,894 802 2,154 per BTX (ppm) Step 3: Removal of Solvent fromSlop Oil through Boiling with Free Water present therein 6 AverageTurbidity of 31 42 35 37 39 40 Slop Oil in NTU on cooling after additionof make-up water that was lost through boiling Step 4: Addition of Alumwith Residence Time in Settling Vessel 7 Wt. % of Alum added 0.05 0.050.05 0.05 0.05 0.05 to Slop Oil 8 Time permitted for 18.32 19.36 24.4524.56 20.40 20.50 Settling (hrs) 9 Average Turbidity 14.9 24 11 10 4.444.7 after above Settling Time (NTU) Step 5: Filtration 10 AverageTurbidity of 3.03 7.32 3.69 2.32 2.59 3.20 Filtrate after using 41 GradeWhatman Filter paper (NTU) 11 Average Turbidity of 0.834 1.32 1.02 0.9481.75 1.78 Filtrate after using 40 Grade Whatman Filter paper (NTU) 12Total time elapsed 20.32 21.36 26.45 26.56 25.4 25.50 since preparationof Slop Oil (hrs) 13 Average Turbidity of 3,866 3,827 — — Control Sampleof same Slop Oil after same time since its preparation (NTU)

Viscous ONGC Hydrocarbons—

TABLE 28.7A PRODUCTION OF VISCOUS ONGC HYDROCARBONS BASED SLOP OILSUSING HIGH SHEAR MIXING MACHINE SI. No. DESCRIPTION TEST 1 TEST 2 TEST 31 Total Mass of Slop Oils (kg) 0.49 0.49 0.51 2 Mixing Time (min) 5.005.00 5.00 3 RPM of Mixing 10,000 10,000 10,000 4 Viscous hydrocarboncontent 2,488 4,995 9,999 in slop oil (ppm) 5 Oil content in slop oil(ppm) 1,232 2,474 4,952 6 Ash content in slop oil (ppm) 206 413 827 7Bound water in slop oil (ppm) 1,050 2,108 4,220 8 Time elapsed beforechecking 3.90 7.19 4.30 of Turbidity (min) 9 Average Turbidity of Slop1,637 3,272 8,633 Oils (NTU)

TABLE 28.7B PROCESSING OF ABOVE SLOP OIL BY COMBINING THE USE OFCENTRIFUGE WITH SOLVENT, ALUM AND THEN FILTRATION SI. No. DESCRIPTIONTEST 1 TEST 2 TEST 3 Step 1: Centrifuging of Slop Oil at 4,500 RCF twicewith NIL Residence time at peak RCF value 1 Average Turbidity of SlopOil after 2nd 876 1174 1540 Centrifuge (NTU) Step 2: Addition of Solvent& then Centrifuging it once under same conditions as above and thenremoval of entire top layer of Solvent + Oil 2 Name & Wt. % Solventadded Xylene Xylene Toluene (5%) (5%) (5%) 3 Mode of Solvent additionVigorous Vigorous High hand hand shear mix mix mixing 4 Time of mixing(min) — — 1 minute 5 RPM used for mixing Solvent — — 8,090 6 AverageTurbidity of Slop Oil after 4,731 3,615 4,176 removal of top layer (NTU)Step 3: Removal of top layer Solvent + Oil 7 Wt. % ONGC Viscoushydrocarbons + 97.37 98.03 96.48 Solvent recovered 8 Wt. % Moisture inabove as per BTX 24,743 29,884 26,112 (ppm) Step 4: Removal of Solventfrom Slop Oil through boiling with Free Water present therein 9 AverageTurbidity of Slop Oil in NTU 236 220 238 on cooling after addition ofmake-up water that was lost through boiling Step 5: Addition of Alumwith Residence Time in Settling Vessel 10 Wt. % of Alum added to SlopOil 0.05 0.05 0.05 11 Time permitted for Settling (hrs) 38.12 38.3 40.0912 Average Turbidity after above Settling 8.91 6.07 5.49 Time (NTU) Step6: Filtration 13 Average Turbidity of Filtrate after using 3.85 2.351.99 41 Grade Whatman Filter paper (NTU) 14 Average Turbidity ofFiltrate after using 0.69 1.26 0.65 40 Grade Whatman Filter paper (NTU)15 Total time elapsed since preparation of 40.12 41,53 41.36 Slop Oil(hrs)

It was observed that when water insoluble solids are present in slopoils, like those containing ONGC viscous hydrocarbons, it was necessaryto incorporate filtration after addition of alum to get low turbidityvalues as filtration was found to be more effective in removing veryfine ash particles. This could be seen from Table 28.7B. It was furtherascertained that the diesel slop oils were the easiest to process.

Further, it was seen that incorporation of all four unit operations likecentrifuge, addition of solvent, addition of alum followed by filtrationin process made processing of the slop oil faster with least operativeproblems and with excellent results. Further, it was seen that thepollution problem was found to be entirely mitigated. Besides, it wasfound that said operations entirely recover almost excellent qualityhydrocarbons and water for use or sale. Energy consumption was found tobe very small. Also, the solvent employed was fully recovered in itsoriginal form for re-use.

It was seen that the quantity of solvent required and mode of solventaddition were dependent on quantity of hydrocarbons present in slopoils. The quantity of solvent required was more when hydrocarbons werelot more and least agitation was needed while adding solvent. It wasseen that mere hand shaking was preferred mode of adding solvent whenhydrocarbon content in slop oils was high as can be clearly seen fromtest 4 in table 28.6B. It was also seen that even mild hand shaking wasequally effective. It was also seen that with collection of hydrocarbonsbecame very easy with the use of solvent. The weight percent collectedalso went up. Finally, it was seen that often solvent cum oil layer washaving very little water therein.

Example-29 Efficacy of the Process of Present Invention with Slop OilsContaining Very High Hydrocarbon Content

It was an aim to study efficacy of the combined process with slop oilshaving very high hydro-carbon content inclusive of recovery ofhydrocarbons and solvent. Accordingly, the slop oils were prepared withCoconut Oil under conditions as mentioned below in table 29.1. Theseslop oil samples were retained in a separating flask for 48 hours thatlead to formation of three layers. The top layer obtained was containingpure oil. The middle layer obtained was containing oil and water bothwhile the bottom layer was containing mostly water with little Oiltherein. The bottom layer was removed and treated as slop oil along withslop oil coming from middle layer as explained below.

The middle Layer was treated with Alum and retained in Separating Flaskfor another 48 hours that lead to further formation of three layers,i.e. top layer containing pure oil, middle layer containing oil and alumwith water and bottom layer of slop oil. The layer containing alum wasdried and tested for Calorific Value. The weight percent recovery ofpure coconut oil from top and middle layers and calorific value of driedalum layer can be seen in table 29.2 while results of treatment of slopoil along with weight percent recovery of coconut oil cum solvent can beseen in table 29.3.

TABLE 29.1 PRODUCTION OF COCONUT OIL BASED SLOP OILS USING HIGH SHEARMIXING MACHINE SI. No. DESCRIPTION TEST 1 TEST 2 1 Total Mass of SlopOils (kg) 0.50 0.50 2 Mixing Time (min) 5 5 3 RPM of Mixing 10,00010,000 4 Oil content in Slop Oil (ppm) 95,921 240,150 5 Time elapsedbefore checking 5.30 4.82 of Turbidity (min) 6 Average Turbidity ofSlop >10,000 >10,000 Oils (NTU)

TABLE 29.2 FRACTION OF OIL COLLECTED FROM DIFFERENT SECTIONS SI. No.DESCRIPTION TEST 1 TEST 2 1 Wt % of Oil collected from top most layer16.38 33.68 2 Wt % of Oil collected from middle layer 63.60 54.16 3Calorific value of Scum obtained from — 8,682 middle layer (kcal/kg) 4Calorific value of Original Coconut Oil 8,972 8,972 (kcal/kg) 5 Wt % ofOil lost adhering to various 7.19 8.82 surfaces

TABLE 29.3 PROCESSING OF BOTTOM LAYER SLOP OIL BY COMBINING THE USE OFCENTRIFUGE WITH SOLVENT, ALUM AND THEN FILTRATION SI. No. DESCRIPTIONTEST 1 TEST 2 Step 1: Centrifuging of Slop Oil at 4,500 RCF twice withNIL Residence time at peak RCF value 1 Average Turbidity of Slop Oilafter 2nd >10,000 >10,000 Centrifuge (NTU) Step 2: Addition of Solvent &Centrifuging it once under same conditions as above and then removal ofentire top layer of Solvent + Oil 2 Name & Wt. % of Solvent added XyleneXylene (25%) (25%) 3 Mode of Solvent addition High High shear shearmixing mixing 4 Time of mixing (min) 1 minute 1 minute 5 Maximum RPMused for mixing Solvent 8,090 8,090 6 Average Turbidity of Slop Oilafter 1,726 1,415 removal of top layer (NTU) Step 3: Removal of toplayer Solvent + Oil 7 Wt. % of Coconut oil + Solvent recovered 96.7094.3 8 Moisture in above as per BTX (ppm) 18,155 16,550 Step 4: Removalof Solvent from Slop Oil through Boiling with Free water present therein9 Average Turbidity of Slop Oil in NTU 60 53 on cooling after additionof make-up water that was lost through boiling Step 5: Addition of Alumwith Residence Time in Settling Vessel 10 Wt. % of Alum added to SlopOil 0.05 0.05 11 Time permitted for Settling (hrs) 17.48 29.96 12Average Turbidity after above Settling 3.15 4.53 Time (NTU) Step 6:Filtration 13 Average Turbidity of Filtrate after using 2.33 3.24 41Grade Whatman Filter paper (NTU) 14 Average Turbidity of Filtrate afterusing 0.748 1.72 40 Grade Whatman Filter paper (NTU) 15 Total timeelapsed since preparation of 25.78 38.11 Slop Oil (hrs)

It was observed that, for a given hydrocarbon, higher the quantum ofhydrocarbons in Slop Oils; easier it was for pure hydrocarbons toseparate out with settling. Also, it was observed that presence of Alumin coconut oil reduced its calorific value by 3.2 wt. % apart frommaking it viscous and increasing its alkali and ash contents.

Example-30 Qualitative and Quantitative Recovery of Hydrocarbons,Solvent and Water from Large Samples of Slop Oils Using Entire Processof the Present Invention

It was an aim to study efficacy of the process of present invention withlarge scale slop oils by evaluating the quantity and quality ofhydrocarbons, solvent and water recovered. Accordingly, the slop oilsamples were prepared as per conditions mentioned in table 30.1. Theslop oils were then treated as per procedure mentioned in table 30.2.Subsequently, hydrocarbons and solvent layer removed from step-3 intable 30.2 was next treated as per procedure mentioned in Example-15 andExample-16. The results obtained can be clearly seen in table 30.3.

TABLE 30.1 PRODUCTION OF VISCOUS ONGC HYDROCARBONS BASED SLOP OILS USINGHIGH SHEAR MIXING MACHINE SI. No. DESCRIPTION TEST 1 TEST 2 Name of OilUsed ONGC Solids Diesel 1 Total Mass of Slop Oils (kg) 20.02 20.13 2Mixing Time (min) 5 13.33 3 RPM of Mixing 10,000 8,130 4 ViscousHydrocarbon containing 9,974 — bound water and ash in Slop Oil (ppm) 5Hydrocarbons content in slop oil 4939 7,446 (ppm) 6 Ash content in Slopoil (ppm) 825 — 7 Bound water in Slop oil (ppm) 4,210 — 8 Time elapsedbefore checking 4.17 4.68 of Turbidity (min) 9 Average Turbidity of SlopOils 7,742 9,264 in (NTU)

TABLE 30.2 PROCESSING OF ABOVE SLOP OIL BY COMBINING THE USE OFCENTRIFUGE WITH SOLVENT, ALUM AND FILTRATION ALONG WITH THE RECOVERY OFOIL SI. No. DESCRIPTION TEST 1 TEST 2 Step 1: Centrifuging of Slop Oilat 4,500 RCF twice with NIL Residence time at peak RCF value 1 AverageTurbidity of Slop Oil after 2nd 1,436 64 Centrifuge (NTU) Step 2:Addition of Solvent & then Centrifuging it once under same conditions asabove and then removal of entire top layer of Solvent + Oil 2 Name & Wt.% of Solvent added Xylene Xylene (5%) (2%) 3 Mode of Solvent additionHigh Vigorous shear hand mixing mix 4 Time of mixing (min) 1 minute — 5RPM used for mixing Solvent 8090 — 6 Average Turbidity of Slop Oil after2,733 78 removal of top layer (NTU) Step 3: Removal of top layerSolvent + Oil 7 Wt. % ONGC Viscous hydrocarbons + 97.11 97.88 Solventrecovered 8 Wt. % Moisture in above as per BTX 25,534 541 (ppm) Step 4:Removal of Solvent from Slop Oil through Boiling with Free Water presenttherein 9 Average Turbidity of Slop Oil in NTU 140 33 after addition ofmake-up water that was lost through boiling (NTU) Step 5: Addition ofAlum with Residence time in Settling Vessel 10 Wt. % of Alum added toSlop Oil 0.05 0.05 11 Time permitted for Settling (hrs) 38.69 18.12 12Average Turbidity after above Settling 4.96 4.64 Time (NTU) Step 6:Filtration 13 Average Turbidity of Filtrate after using 2.13 2.54 41Grade Whatman Filter paper (NTU) 14 Average Turbidity of Filtrate afterusing 0.47 0.95 40 Grade Whatman Filter paper (NTU) 15 Total timeelapsed since preparation of 40.7 25.3 Slop Oil (hrs)

TABLE 30.3 SEPARATION OF SOL VENT FROM OIL SI. No. DESCRIPTION ONGCSolids Diesel Step 1: Addition of Water & Boiling 1 Wt of Solvent & Oiltaken (kg) 1.0989 0.5469 2 Wt of Free Water added (kg) 2.0088 0.8052 3Max. Temp in ° C. while Boiling 97.2 97.4 4 Wt of Solvent collected as1.0135 0.4092 condensate (kg) 5 Wt of Water collected as 0.896 0.3543condensate (kg) 6 Wt of Free Water & Oil remaining in 1.181 0.5792 RBflask in (kg) Step 2: Hot Centrifuging at 4,500 RCF once with residencetime of 10 minutes 7 Temp. in ° C. of Free Water & 92.3 92 Oil at thestart of Centrifuging 8 Moisture in Oil after Step 2 as 25,700 342 perBTX (ppm) 9 Average Turbidity of recovered 13.6 4.2 Free Water afterStep 2 (NTU)

TABLE 30.4 TEST RESULTS SI. No. DESCRIPTION ONGC Solids Diesel 1 Wt. %Solvent recovered for Reuse 99.25 99.65 inclusive of material adheringon glasswares 2 Moisture in recovered Solvent as 56 48 per BTX (ppm) 3Wt. % Hydrocarbons recovered 94.89 95.31 inclusive of material adheringon glasswares 4 Moisture in recovered Oil as per 25,700 342 BTX (ppm) 5Calorific value of recovered Oil 10,428 11,027 (kcal/kg) 6 Calorificvalue of original Oil 10,652 11,002 (kcal/kg) 7 Wt. % of Water recoveredfrom Slop 98.15 98.86 Oil inclusive of materials adhering on glasswares8 Final Turbidity of above Water 0.47 0.95 (NTU) 9 Wt. % of Free Waterthat was used 98.08 98.38 for Solvent/Oil separation recovered for reuseinclusive of materials adhering on glasswares 10 Average Turbidity ofFree Water 13.6 4.2 recovered for reuse (NTU)

It was observed that the qualitative cum quantitative recoveries ofsolvent and water from above slop oils were extremely good. It wasfurther seen that small fractions of hydrocarbons were boiled out withsolvent thus depressing its weight percent recovery. Finally, it wasseen that moisture in ONGC hydrocarbons could have been lower if saidprocess had opted for hot settling over 48 hours. Finally, it wasobserved that it was lot more difficult to remove free water fromviscous hydrocarbons.

The present invention has been described in an illustrative manner, andit is to be understood that the terminology used is intended to be inthe nature of description rather than of limitation. It is not intendedto be exhaustive or to limit the invention to the precise formdisclosed. Many modifications and verifications are possible in light ofthe above teaching. It is intended that the scope of the invention belimited not by this detailed description, but rather by the claimsappended hereto. It is also to be understood that the following claimsare intended to cover all of the generic and specific features of theinvention described herein.

1. A process for treatment of a sludge mixture having hydrocarbons withbound water, unbound water, dissolved and un-dissolved solids therein,the process for treatment of the sludge mixture comprising the steps of:a) Centrifuging the sludge mixture in a first centrifuge provided thesludge mixture splits into various components, the first centrifugebeing a batch or Multi-Pass centrifuge, the said centrifuge forming aviscous hydrocarbon layer, a slop oil layer and a free flowinghydrocarbon layer; b) Desalting the viscous hydrocarbon layer from stepa) in a first desalter followed by optional treatment thereof in a heatbased low volatiles stripping vessel for removing vapors of low boilingliquid hydrocarbons therefrom; c) Condensing the vapors of low boilingliquid hydrocarbons from step b) in a first condenser for obtaining lowboiling liquid hydrocarbons along with water for use; d) Optionallydesalting crude hydrocarbons coming from a group collection center in asecond desalter for obtaining desalted product crude and removal of abound water containing hydrocarbon layer followed by mixing the boundwater containing hydrocarbon layer with the viscous hydrocarbon layerfrom the first centrifuge; e) Desalting the free flowing hydrocarbonlayer from step a) in a third desalter for entire removal of saltstherefrom; f) Homogenizing the viscous hydrocarbon layer from step b) ina homogenizer by adding a first predefined amount of solvent for forminga volatiles free non-viscous homogenized stream therefrom; g) PerformingBTX and Ash tests of the non-viscous homogenized stream from step f)followed by treatment thereof in an agitator cum homogenizer therebyadding a second predefined amount of solvent therein in accordance withthe BTX and Ash tests results; h) Centrifuging the non-viscoushomogenized stream from step g) in a second centrifuge for separating abound water dominant hydrocarbon stream, an unbound water dominant orwater free hydrocarbon stream and the slop oil therefrom; i) Optionallytreating the non-viscous homogenized stream from step g) in a hotinsulated settling tank for removal of water free solvent along withhydrocarbons therefrom; j) Heating the unbound water dominant or waterfree hydrocarbon stream from step h) in a first heating vessel therebyoptionally adding a predefined amount of free water therein, the firstheating vessel operating at a first predefined temperature range therebyforming a first residual phase and a first vapor phase therein; k)Heating the bound water dominant hydrocarbon stream from step h) in asecond heating vessel at a second temperature range thereby optionallyadding a third predefined amount of additional solvent therein, thesecond heating vessel forming a second residual phase and a second vaporphase therein; l) Centrifuging the first residual phase from step j) ina hot centrifuge at a second predefined temperature for obtainingvolatiles free desalted product hydrocarbons in a range of about 96 wt %to 100 wt % along with unbound water having turbidity at least below 20NTU; m) Treating the second residual phase from step k) in the firstheating vessel; and n) Condensing the first vapor phase from step j) andthe second vapor phase from step k) through a second condenser forobtaining almost 100% solvent, the bound water in a range of about 99 wt% to 100 wt % wherein the free water in a range of about 94 wt. % to 100wt. % is collected through the entire process, the solvent being reusedin said process.
 2. The process for treatment of the sludge mixture asclaimed in claim 1, wherein the first centrifuge substantially reducesthe quantum of the sludge mixture with bound water that facilitatesfurther processing with reduced cost and time in downstream processingof said process.
 3. The process for treatment of the sludge mixture asclaimed in claim 1, wherein the free flowing hydrocarbon layer is about41 wt % typically having 3,864 ppm water and 0.88 wt. % ash withcalorific value of 10,635 kcal/kg.
 4. The process for treatment of thesludge mixture as claimed in claim 1, wherein the viscous hydrocarbonlayer has at least 42.21 wt. % water typically having 8.61 wt. % Ashwith CV of 5,210 kcal/kg.
 5. The process for treatment of the sludgemixture as claimed in claim 1, wherein the first centrifuge enhancesseparation between the components present in the sludge by extending aperiod of residence time of the sludge thereby gradually varyingrevolutions per minute of the batch centrifuge enabling collection ofslop oil behind the viscous hydrocarbon layer. 6-7. (canceled)
 8. Theprocess for treatment of the sludge mixture as claimed in claim 1,wherein the first desalter, the second desalter and the third desalterprevent ingression of water into various product hydrocarbon streams inrefineries thereby preventing accumulation of sludge downstream of saidprocess and in vessels utilized in refinery onward processes. 9-11.(canceled)
 12. The process for treatment of the sludge mixture asclaimed in claim 1, wherein removal of the bound water from thehydrocarbon layer allows removal of heavy metal, ash and salts therefromfor effectively improving commercial value.
 13. The process fortreatment of the sludge mixture as claimed in claim 1, wherein the BTXand Ash tests help assist in determination of an optimum amount ofsolvent to be added in said process.
 14. The process for treatment ofthe sludge mixture as claimed in claim 1, wherein the solvent reducesviscosity for removal of bound water from topmost layer of thenon-viscous homogenized stream on account of viscosity.
 15. The processfor treatment of the sludge mixture as claimed in claim 1, wherein thesolvent assists in homogenization of the sludge that in turn helps insampling and accurate determination of water and ash content.
 16. Theprocess for treatment of the sludge mixture as claimed in claim 1,wherein the solvent is added in said process only for viscous portion ofthe hydrocarbons which substantially reduces overall use of solvent insaid process.
 17. The process for treatment of a sludge mixture asclaimed in claim 1, wherein the solvent is selected from the group ofBenzene, Toluene, Xylene and similar solvents which can form azeotropeswith water.
 18. (canceled)
 19. The process for treatment of the sludgemixture as claimed in claim 1, wherein the solvent¾tream and the secondcentrifuge mutually remove substantial bound water from the viscoushydrocarbon layer at an ambient temperature.
 20. The process fortreatment of the sludge mixture as claimed in claim 1, wherein thesolvent depresses the boiling point of the bound water.
 21. The processfor treatment of the sludge mixture as claimed in claim 1, wherein thesolvent is added in a range of about 1.8 to 100 times the weight ofwater present in the sludge for entire removal of the bound water. 22.The process for treatment of the sludge mixture as claimed in claim 1,wherein the solvent has a left over weight ratio of solvent tohydrocarbon in a minimum range of 2.00 to 6.00 for entire removal of thebound water at least temperature.
 23. The process for treatment of thesludge mixture as claimed in claim 1, wherein the first predefinedtemperature of the first heating vessel is in a range of about 90°C.-105° C.
 24. The process for treatment of the sludge mixture asclaimed in claim 1, wherein, the hot centrifuge has a temperature in arange of about 80° C. to 94° C.
 25. The process for treatment of thesludge mixture as claimed in claim 1, wherein the hot centrifuge is ahot settling tank that ensures adequate reduction in viscosity ofhydrocarbons thereby allowing settling of free water therein over apredefined period of time.
 26. The process for treatment of the sludgemixture as claimed in claim 25, wherein the hot settling tank isoperated under high pressure for increasing the operating temperaturerange for further reducing the viscosity of the hydrocarbon therebyfacilitating faster removal of free water without leading to boiling ofwater therein.
 27. process for treatment of the sludge mixture asclaimed in claim 1, wherein the second heating vessel is preferably amulti effect evaporator preferably with a thermal vapor recompression toavoid thermal cracking of the product hydrocarbon stream.
 28. Theprocess for treatment of the sludge mixture as claimed in claim 1,wherein one or both of the first and second heating vessel includes afoam breaker and an entrainment separator adapted to avoid entrainmentof hydrocarbons in condensate, and optionally the first and secondheating vessels are provided with waste heat for reducing cost of energyin said process.
 29. (canceled)
 30. The process for treatment of thesludge mixture as claimed in claim 1, wherein the second heating vesselmaintain a controlled rate of heating with an optimum ratio of residualsolvent to dehydrated Hydrocarbon for complete removal of bound waterfrom the hydrocarbon.
 31. The process for treatment of the sludgemixture as claimed in claim 1, wherein the bound water obtained is highquality usable water that requires minimal treatment for being used as adrinking water. 32-33. (canceled)
 34. A process for treatment of slopoil containing water, solids, salts, and hydrocarbons with or withoutbound water, the process comprising the steps of: a) Centrifuging theslop oil through a fourth centrifuge for obtaining the slop oil with lowturbidity by connecting most oil present in a thin top layer; b)Treating the above slop oil from step a) in a high speed shear mixer byadding a solvent to form a mixture followed by centrifuging thereof in afifth centrifuge for obtaining a water dominant hydrocarbon layer and asolvent dominant hydrocarbon layer therefrom; c) Performing BTX and Ashtests of the solvent dominant hydrocarbon layer from step b) for boundwater therein followed by a heat treatment thereof in a third heatingvessel and a fourth heating vessel, the third vessel having a predefinedamount of solvent added therein, the fourth vessel having a predefinedamount of free water added therein, the third heating vessel and fourthheating vessel separating a vapor phase from a liquid phase, the vaporphase having entire remaining solvent and part of free water therein,the liquid phase having hydrocarbons with limited solids, limited salts,free water and alum therein; d) Centrifuging the liquid phase from stepc) through a sixth centrifuge operating at a predefined temperature forseparating a product hydrocarbon layer from a water layer, the waterlayer having limited salts, limited solids and alum therein; e) Treatingthe water layer from step d) through a first reverse osmosis plant forobtaining water for use and a reject stream therefrom; f) Condensing thevapor phase from step c) through a third condenser for obtaining solventfor being reused in the high speed shear mixer and water for usetherefrom; g) Heating the water dominant hydrocarbon layer from step b)in a fifth heating vessel for separating vapors of solvent therefromfollowed by condensing thereof in the third condenser to obtain solventfor reuse and water for use therefrom, the fifth heating vesselproducing a liquid phase having remaining water, limited hydrocarbons;salts and solids with a substantially low turbidity; h) Treating theliquid phase from step g) in a settling tank followed by addition of apredefined amount of alum therein, the settling tank forming a waterdominant alum layer and a gelatinous oil bearing layer therein; i)Filtering the water dominant alum layer from step h) in a filtrationunit, the filtration unit separating the water dominant alum layer intoa filtrate stream and a residual stream, the filtrate stream havingwater, alum and salts therein, the residual stream having wet solidswith traces of hydrocarbons, salts and alum therein; j) Treating thefiltrate stream from step i) in a second reverse osmosis plant forrecovering usable water therefrom; k) Mixing the residual stream fromstep i) with the gelatinous oil bearing layer followed by drying thereofin a first hot dryer for obtaining a viscous liquid containinghydrocarbons, alum, solids and salts; l) Agitating the viscous liquidfrom step k) in an agitator cum de-oiling unit by adding a predefinedsolvent therein followed by treatment thereof through a seventhcentrifuge for obtaining a water layer, a cake layer and a solvent layerthereby adding water therein, the water layer having alum, salts andlimited solvent therein, the cake layer having cake of de-oiled solidswith solvent, limited salts and limited alum therein; m) Treating thewater layer from step l) in a sixth heating vessel for obtaining vaporsof solvent and water followed by treatment thereof through a fourthcondenser for obtaining solvent for reuse and water for use or furthertreatment in said process; n) Treating the solvent layer from step l) inthe fourth heating vessel for recovery of solvent therefrom; and o)Treating the cake layer from step l) in a second hot dryer for recoveryof solvent through the condenser, the second hot dryer producing driedde-oiled solids having traces of alum and salts therein. 35-59.(canceled)
 60. A process for treatment of a sludge mixture comprising ofa centrifuge, the process for treatment comprising the steps of:Centrifuging the sludge containing hydrocarbons, bound and unboundwater, salts and solids in a centrifuge to break the binding between thecomponents present by increasing residence time of the sludge in thecentrifuge thereby forming a viscous hydrocarbon layer with bound water,salts and solids, a free flowing hydrocarbons layer with limited saltsand solids and a free water layer with limited solids and salts, thecentrifuge repositioning the viscous hydrocarbon layer from a back sideto a middle side therein by slowly increasing revolutions per minutesthereof, the centrifuge slowly decreasing an angle between a verticalaxis of a container and a horizontal plane thereof thereby graduallyreducing but not allowing said angle to become 0°. 61-62. (canceled) 63.A process for treatment of sludge mixture with combined effect ofcentrifuge and solvent, the sludge mixture containing bound and unboundwater, salts and solids therein, the process for treatment comprisingthe steps of: a) Adding a predefined amount of solvent in the viscoushydrocarbon layer from step a), followed by mixing thereof, the solventreducing the viscosity of the viscous hydrocarbon layer. b) Centrifugingthe solvent dominant viscous hydrocarbon layer from step a) in thecentrifuge to obtain a large layer of solvent and hydrocarbon, a layercontaining hydrocarbons and bound water and a free water layer, thecentrifuge having an extended residence time to produce less sludge withbound water therein; c) Treating the large layer of solvent andhydrocarbon in step b) to recover solvent by boiling through free waterin a temperature range of 90° C. to 99° C. at an atmospheric pressure.64-65. (canceled)